Question

3g^2 - 12g = - 4
which number will complete the square?
a. 12
b. -4
c. 4
d. 36

Answer 1

if you factor out the 3 on the left, you'll get

\(\large 3(g^2-4g)=-4\)

Then to complete the square, add the square of half the coefficient of g.

Answer 2

Then, consider what would have to be added to the right side to keep both sides equal.

Answer 3

4?

Answer 4

@CliffSedge

Answer 5

Right, adding 4 inside the parentheses on the left yields

\(\large 3(g^2-4g+4)=-4 + ?\)

Answer 6

so 4 completes the square then?

Answer 7

47

Answer 8

47?

Answer 9

What happens when you distribute that 3 back into those parentheses on the left?

Answer 10

3g^2-12g+12

Answer 11

Right, so you actually added 12 to both sides to complete the square.

\(\large 3g^2−12g+12)=−4+12\).

See?

Answer 12

oh got it thanks!