### Home > AC > Chapter 2 > Lesson 2.1.2 > Problem2-18

2-18.

Remember that one meaning of the word “evaluate” is to replace a variable with a number and to calculate the result. For example, when asked to evaluate the expression $x^2$ when $x=−2$, the solution would be $(−2)^2=4$.

Evaluate the expressions below for the given values.

1. $−4d + 3\ \text{if}\ d= −1$

Substitute $−1$ for $d$.

$−4(−1)+3$

Simplify the terms and combine them.

$4+3=7$

$7$

1. $k − m\ \text{if}\ k= 4\ \text{and}\ m= −10$

Follow the steps in part (a).

Put everything you substituted inside parentheses so you do not lose your negative signs.

$(4)−(−10)$

1. $\frac{t}{w}\ \text{if}\ t= 6\ \text{and}\ w= −3$

Follow the steps in part (a).

$−2$

1. $x^2 + y^2\ \text{if}\ x = 7\ \text {and}\ y = 5$

Follow the steps in part (a).