Question

pre-algebra #10
3.) $-4 - 3x$ if $x = -2$
$-4 + -3x =$
4.) $-3x - 4$ if $x = -1$
5.) $5 - 2x$ if $x = 2$
6.) $2x - 5$ if $x = 2$
7.) $7 - 4y$ if $y = -8$
8.) $-4x - 8$ if $x = 2$
1.) 10 2.) -14 5.) 1
example 3: evaluate $-4xy$ if $x = -2$ and $y = -3$.
$-4xy = -4( )( ) = -4(-2)(-3) =
(8)(-3) =
-24$
$x = -2$
$y = -3$
in this example we have two variables in the
expression and must substitute a value for each one.
when variables and constants are written next to
each other, multiplication is indicated. remember
to put parentheses each time you substitute a value
for a variable.
remember, you can only
multiply two numbers at a time.
practice exercises; evaluate for the given values of the variables. remember
1.) $2xy$ if $x = -1$, $y = -3$
$2(6)(3) = -45$
2.) $-3xy$ if $x = 3$, $y = -4$
3.) $5xy$ if $x = -3$, $y = 3$
4.) $-6ab$ if $a = 2$, $b = 3$
5.) $3xy$ if $x = 1$ and $y = -2$
6.) $-2rs$ if $r = 0$ and $s = 2$
7.) $-3xy$ if $x = -1$ and $y = -2$
8.) $4cd$ if $c = -2$ and $d = -3$
1.) 6 3.) -45

Explanation:

Step1: Substitute x value

Substitute \( x = -2 \) into \( -4 - 3x \). So the expression becomes \( -4 - 3(-2) \).

Step2: Multiply

Calculate \( -3(-2) = 6 \). Now the expression is \( -4 + 6 \).

Step3: Add

Add \( -4 + 6 = 2 \).

Answer:

2