{"id":735,"date":"2025-07-15T14:55:54","date_gmt":"2025-07-15T14:55:54","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/precalculus\/?post_type=chapter&#038;p=735"},"modified":"2026-01-09T20:52:04","modified_gmt":"2026-01-09T20:52:04","slug":"graphs-of-linear-functions-learn-it-4","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/precalculus\/chapter\/graphs-of-linear-functions-learn-it-4\/","title":{"raw":"Graphs of Linear Functions: Learn It 4","rendered":"Graphs of Linear Functions: Learn It 4"},"content":{"raw":"<h2 data-start=\"497\" data-end=\"547\">Finding the [latex]y[\/latex]-intercept of a Line<\/h2>\r\n<p data-start=\"270\" data-end=\"608\">Another key feature of a linear function is the [latex]y[\/latex]-intercept: the point at which the graph of a function crosses the [latex]y[\/latex]-axis. The [latex]y[\/latex]-intercept is the [latex]y[\/latex]-coordinate of the point where the input value is zero.<\/p>\r\n<p data-start=\"610\" data-end=\"796\">To find the [latex]y[\/latex]-intercept, substitute [latex]x = 0[\/latex] into the function and solve for [latex]f(x)[\/latex] or [latex]y[\/latex]. For example, consider the function shown:<\/p>\r\n<p style=\"text-align: center;\" data-start=\"798\" data-end=\"835\">[latex]f\\left(x\\right)=3x - 6[\/latex]<\/p>\r\n<p data-start=\"837\" data-end=\"887\">Substitute [latex]x = 0[\/latex] into the function:<\/p>\r\n<p style=\"text-align: center;\" data-start=\"889\" data-end=\"967\">[latex]\\begin{array}{l}f(0)=3(0) - 6\\hfill \\\\ f(0)=0 - 6\\hfill \\\\ f(0)=-6\\hfill \\end{array}[\/latex]<\/p>\r\n<p data-start=\"969\" data-end=\"1065\">The graph of the function crosses the [latex]y[\/latex]-axis at the point [latex](0, -6)[\/latex].<\/p>\r\n\r\n<section class=\"textbox keyTakeaway\" aria-label=\"Key Takeaway\">\r\n<h3>[latex]y[\/latex]-intercept of a Line<\/h3>\r\nThe [latex]y[\/latex]-intercept of a function is the value of [latex]f(x)[\/latex] when [latex]x = 0[\/latex].\r\nIn slope-intercept form, [latex]f(x) = mx + b[\/latex], the [latex]y[\/latex]-intercept is the constant [latex]b[\/latex].\r\n\r\n&nbsp;\r\n\r\nIn context, the [latex]y[\/latex] typically represents the initial value or starting point of the function.\r\n\r\n<\/section><section class=\"textbox example\" aria-label=\"Example\">\r\n<h3 data-start=\"1349\" data-end=\"1360\">Find the [latex]y[\/latex]-intercept of the following:<\/h3>\r\n<p data-start=\"1659\" data-end=\"1706\">[latex]f\\left(x\\right)=\\frac{1}{2}x - 3[\/latex]<\/p>\r\n<p data-start=\"1708\" data-end=\"1845\">[reveal-answer q=\"400057\"]Show Solution[\/reveal-answer]<br data-start=\"1763\" data-end=\"1766\" \/>[hidden-answer a=\"400057\"]<br data-start=\"1792\" data-end=\"1795\" \/>Substitute [latex]x = 0[\/latex] into the function:<\/p>\r\n<p data-start=\"1847\" data-end=\"1935\">[latex]\\begin{array}{l}f(0)=\\frac{1}{2}(0) - 3\\ f(0)=0 - 3\\ f(0)=-3\\end{array}[\/latex]<\/p>\r\n<p data-start=\"1937\" data-end=\"2251\">The graph crosses the [latex]y[\/latex]-axis at the point [latex](0, -3)[\/latex].<br data-start=\"2017\" data-end=\"2020\" \/>[latex]\\[\/latex]<br data-start=\"2037\" data-end=\"2040\" \/><strong data-start=\"2040\" data-end=\"2068\">Analysis of the Solution<\/strong><br data-start=\"2068\" data-end=\"2071\" \/>A graph of the function is shown below. We can see that the line crosses the [latex]y[\/latex]-axis at [latex]-3[\/latex], confirming the [latex]y[\/latex]-intercept.\r\n[\/hidden-answer]<\/p>\r\n\r\n<\/section><section class=\"textbox example\" aria-label=\"Example\">Find the [latex]y[\/latex]-intercept of the graph. <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010639\/CNX_Precalc_Figure_02_01_0132.jpg\" \/>\r\n<p data-start=\"1708\" data-end=\"1845\">[reveal-answer q=\"400058\"]Show Solution[\/reveal-answer]<br data-start=\"1763\" data-end=\"1766\" \/>[hidden-answer a=\"400058\"]<br data-start=\"1792\" data-end=\"1795\" \/>The [latex]y[\/latex]-intercept is the point where the line crosses the [latex]y[\/latex]-axis. On this graph, the [latex]y[\/latex]-intercept is [latex](0,-7)[\/latex].\r\n[\/hidden-answer]<\/p>\r\n\r\n<\/section><section class=\"textbox proTip\" aria-label=\"Pro Tip\">The [latex]y[\/latex]-intercept is always written in the form [latex](0,y)[\/latex].<\/section><section aria-label=\"Pro Tip\"><section class=\"textbox tryIt\" aria-label=\"Try It\">[ohm_question hide_question_numbers=1]317629[\/ohm_question]<\/section><\/section>","rendered":"<h2 data-start=\"497\" data-end=\"547\">Finding the [latex]y[\/latex]-intercept of a Line<\/h2>\n<p data-start=\"270\" data-end=\"608\">Another key feature of a linear function is the [latex]y[\/latex]-intercept: the point at which the graph of a function crosses the [latex]y[\/latex]-axis. The [latex]y[\/latex]-intercept is the [latex]y[\/latex]-coordinate of the point where the input value is zero.<\/p>\n<p data-start=\"610\" data-end=\"796\">To find the [latex]y[\/latex]-intercept, substitute [latex]x = 0[\/latex] into the function and solve for [latex]f(x)[\/latex] or [latex]y[\/latex]. For example, consider the function shown:<\/p>\n<p style=\"text-align: center;\" data-start=\"798\" data-end=\"835\">[latex]f\\left(x\\right)=3x - 6[\/latex]<\/p>\n<p data-start=\"837\" data-end=\"887\">Substitute [latex]x = 0[\/latex] into the function:<\/p>\n<p style=\"text-align: center;\" data-start=\"889\" data-end=\"967\">[latex]\\begin{array}{l}f(0)=3(0) - 6\\hfill \\\\ f(0)=0 - 6\\hfill \\\\ f(0)=-6\\hfill \\end{array}[\/latex]<\/p>\n<p data-start=\"969\" data-end=\"1065\">The graph of the function crosses the [latex]y[\/latex]-axis at the point [latex](0, -6)[\/latex].<\/p>\n<section class=\"textbox keyTakeaway\" aria-label=\"Key Takeaway\">\n<h3>[latex]y[\/latex]-intercept of a Line<\/h3>\n<p>The [latex]y[\/latex]-intercept of a function is the value of [latex]f(x)[\/latex] when [latex]x = 0[\/latex].<br \/>\nIn slope-intercept form, [latex]f(x) = mx + b[\/latex], the [latex]y[\/latex]-intercept is the constant [latex]b[\/latex].<\/p>\n<p>&nbsp;<\/p>\n<p>In context, the [latex]y[\/latex] typically represents the initial value or starting point of the function.<\/p>\n<\/section>\n<section class=\"textbox example\" aria-label=\"Example\">\n<h3 data-start=\"1349\" data-end=\"1360\">Find the [latex]y[\/latex]-intercept of the following:<\/h3>\n<p data-start=\"1659\" data-end=\"1706\">[latex]f\\left(x\\right)=\\frac{1}{2}x - 3[\/latex]<\/p>\n<p data-start=\"1708\" data-end=\"1845\">\n<div class=\"qa-wrapper\" style=\"display: block\"><button class=\"show-answer show-answer-button collapsed\" data-target=\"q400057\">Show Solution<\/button><br data-start=\"1763\" data-end=\"1766\" \/><\/p>\n<div id=\"q400057\" class=\"hidden-answer\" style=\"display: none\"><br data-start=\"1792\" data-end=\"1795\" \/>Substitute [latex]x = 0[\/latex] into the function:<\/p>\n<p data-start=\"1847\" data-end=\"1935\">[latex]\\begin{array}{l}f(0)=\\frac{1}{2}(0) - 3\\ f(0)=0 - 3\\ f(0)=-3\\end{array}[\/latex]<\/p>\n<p data-start=\"1937\" data-end=\"2251\">The graph crosses the [latex]y[\/latex]-axis at the point [latex](0, -3)[\/latex].<br data-start=\"2017\" data-end=\"2020\" \/>[latex]\\[\/latex]<br data-start=\"2037\" data-end=\"2040\" \/><strong data-start=\"2040\" data-end=\"2068\">Analysis of the Solution<\/strong><br data-start=\"2068\" data-end=\"2071\" \/>A graph of the function is shown below. We can see that the line crosses the [latex]y[\/latex]-axis at [latex]-3[\/latex], confirming the [latex]y[\/latex]-intercept.\n<\/div>\n<\/div>\n<\/section>\n<section class=\"textbox example\" aria-label=\"Example\">Find the [latex]y[\/latex]-intercept of the graph. <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010639\/CNX_Precalc_Figure_02_01_0132.jpg\" alt=\"image\" \/><\/p>\n<p data-start=\"1708\" data-end=\"1845\">\n<div class=\"qa-wrapper\" style=\"display: block\"><button class=\"show-answer show-answer-button collapsed\" data-target=\"q400058\">Show Solution<\/button><br data-start=\"1763\" data-end=\"1766\" \/><\/p>\n<div id=\"q400058\" class=\"hidden-answer\" style=\"display: none\"><br data-start=\"1792\" data-end=\"1795\" \/>The [latex]y[\/latex]-intercept is the point where the line crosses the [latex]y[\/latex]-axis. On this graph, the [latex]y[\/latex]-intercept is [latex](0,-7)[\/latex].\n<\/div>\n<\/div>\n<\/section>\n<section class=\"textbox proTip\" aria-label=\"Pro Tip\">The [latex]y[\/latex]-intercept is always written in the form [latex](0,y)[\/latex].<\/section>\n<section aria-label=\"Pro Tip\">\n<section class=\"textbox tryIt\" aria-label=\"Try It\"><iframe loading=\"lazy\" id=\"ohm317629\" class=\"resizable\" src=\"https:\/\/ohm.lumenlearning.com\/multiembedq.php?id=317629&theme=lumen&iframe_resize_id=ohm317629&source=tnh\" width=\"100%\" height=\"150\"><\/iframe><\/section>\n<\/section>\n","protected":false},"author":13,"menu_order":9,"template":"","meta":{"_candela_citation":"[]","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"part":61,"module-header":"learn_it","content_attributions":[],"internal_book_links":[],"video_content":null,"cc_video_embed_content":{"cc_scripts":"","media_targets":[]},"try_it_collection":null,"_links":{"self":[{"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/735"}],"collection":[{"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/users\/13"}],"version-history":[{"count":9,"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/735\/revisions"}],"predecessor-version":[{"id":5264,"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/735\/revisions\/5264"}],"part":[{"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/parts\/61"}],"metadata":[{"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/735\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/media?parent=735"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapter-type?post=735"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/contributor?post=735"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/license?post=735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}