Simplify. Then evaluate each expression as directed. Find the value of 3x+5(x+9)-4x, when x=-5.

Question

 Find the value of 3x+5(x+9)-4x, when x=-5.

Answer 1

3x + 5(x+9) - 4x  when x = -5  

(substitute x with -5)

Here are the steps:  

1.  +3 times -5 = -15

2. +5 times -5 = -25

3.  +5 times +9 = +45

4.  -4 x -5 = +20

Then you add:  -15 -25 +45 +20 = 25

example:  -15-25= -40+45 = +5 +20 =25

 

 

Answer 2

3x+5(x+9)-4x  = 3x+5x+45-4x = 8x+45-4x = 4x+45

Substitute x= -5

4*-5 + 45 = -20 + 45 = 25