CPM Homework Help : AC Problem 2-10

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2-10.

One meaning of the word evaluate is to find the value of an expression. To evaluate, replace a variable with a number and calculate the result. For example, when you are asked to evaluate the expression $4x−2$ when $x=−7$ , you would put $−7$ in place of the variable and calculate: $4(−7)−2=−30$
Evaluate the expressions below for the given values of $x$ and $y$ .

Hint:

Rewrite the expression with the number in place of the variable and simplify if possible.

$\frac{6}{x}+9$ if $x=3$

Step 1 (a):

$\frac{ 6 }{(3) } + 9 =$

Hint (a):

$\text{Remember }\frac{6}{3} \text{ is the same as }6 \text{ divided by }3.$

Answer (a):

$11$

$8x−3+y$ if $x=2$ and $y=1$

Step 1 (b):

$8(2)−3+(1)$

Hint (b):

Try evaluating this one on your own. Think of the rules for multiplying positive and negative integers.

$2xy$ if $x=5$ and $y=−3$

Step 1 (c):

$2(5)(−3)=10(−3)$

Answer (c):

$−30$

$2x^2−y$ if $x=3$ and $y=8$

Step 1 (d):

$2(3)^2−(8)$

Hint (d):

Try evaluating this one on your own. You have already been given a head start.