Question

Andre is solving the equation 4(x + 3) = 7. He says,"I can subtract from each side to get

4x = 1 and then divide by 4 to get x = "Kiran says, "I think you made a mistake."

a. How can Kiran know for sure that Andre's
solution is incorrect?

b. Describe Andre's error and explain how to
correct his work.

Answer 1

x=-1.25

Explanation:

well he was wrong about the 4x = 1.

4(x+3)=7

4x+12=7 1. - 12 on both sides

4x=-5 2. 4 on both sides

x=-1.25

Answer 2

Explanation:

Kiran can know for sure that it is incorrect by substituting x with 1/4

Solving for the equation gives 4(1/4 + 3) = 7
distributing gives 1 + 3 = 7
obviously this is incorrect

b)
Andre's error is that he didnt distribute 7
Distributing 7 results in
4x + 12 = 7
then subtracting 12 from both sides
4x = -5
x = -5/4