Substitute one or more numbers in for one or more variables and simplify
Evaluate Multivariable Algebraic Expressions
The process for evaluating multivariable algebraic expressions is very similar to evaluating algebraic expressions with one variable. The only difference is that instead of substituting a number in for one variable, you will have to substitute one or more numbers in for multiple variables. The rest of the process is the same!
Evaluate [latex]3x+4y - 6[/latex] when [latex]x=10[/latex] and [latex]y=2[/latex].
This expression contains two variables, so we must make two substitutions.
[latex]3x+4y-6[/latex]
Substitute [latex]\color{red}{10}[/latex] for [latex]x[/latex] and [latex]\color{blue}{2}[/latex] for [latex]y[/latex].
When [latex]x=10[/latex] and [latex]y=2[/latex], the expression [latex]3x+4y - 6[/latex] has a value of [latex]32[/latex].
Evaluate [latex]2{x}^{2}+3x+8[/latex] when [latex]x=4[/latex].
We need to be careful when an expression has a variable with an exponent. In this expression, [latex]2{x}^{2}[/latex] means [latex]2\cdot x\cdot x[/latex] and is different from the expression [latex]{\left(2x\right)}^{2}[/latex], which means [latex]2x\cdot 2x[/latex].
[latex]2x^2+3x+8[/latex]
Substitute [latex]\color{red}{4}[/latex] for each [latex]x[/latex].