Question

T

3
Andre solved an equation, but when he checked his
answer he saw his solution was incorrect. He knows he
made a mistake, but he can't find it. Where is Andre's
mistake?
12x – 5 = 3(x + 4)
12x – 5 = 3x + 4
12x = 3x - 1
9x = -1
r
9x
-
9
9
What is the solution to the equation?
1
x=
9
Submit

Answer 1

His mistake was he didn't multiply 3(4) when he was opening the parenthesis

Explanation:

Correct solution:

12x – 5 = 3(x + 4)

Open parenthesis

12x – 5 = 3x + 12

Collect like terms

12x - 3x = 12 + 5

9x = 17

x = 17/9

x = 9 8/9

Incorrect solution:

12x – 5 = 3(x + 4)

His mistake was he didn't multiply 3(4) when he was opening the parenthesis

12x – 5 = 3x + 4

12x = 3x - 1

9x = -1

r

9x

-

9