Question

I need help with completing a square.

Answer 1

y = -2x^2 - 16x + 1

Answer 2

@amistre64 @ranga

Answer 3

Make the x^2 coefficient 1 by factoring out -2:
y = -2x^2 - 16x + 1 = -2(x^2 + 8x - 1/2)
To complete the square, divide the coefficient of x by 2. 8/2 = +4. This is the number that will go inside the parenthesis with x to be squared. Subtract 4^2.
y = -2{ (x + 4)^2 - 4^2 - 1/2 }
= -2{ (x + 4)^2 - 16 - 0.5 )
= -2{ (x + 4)^2 - 16.5 }
y = -2(x + 4)^2 + 33

Answer 4

and can you help me with another one?

Answer 5

y = x^2 + 4x

Answer 6

not funny

Answer 7

Follow the same procedure. Divide the coefficient of x by 2: 4/2 = 2.
This 2 will go inside the parenthesis to be squared and you will have to subtract 2^2
y = x^2 + 4x
y = (x + 2)^2 - 2^2
y = (x + 2)^2 - 4

Answer 8

Ohh.. so y = (x+2)^2 - 4 is the answer? (-2,-4) ? @ranga

Answer 9

If you are asked to find the vertex, then (-2, -4) is the vertex.
If you are simply asked to complete the square as stated in the problem, then y = (x + 2)^2 - 4 is the answer.