Question

Find the perfect C value that completes the square.

f(x)=x²-16x.

Answer 1

+ 64

Explanation:

f(x) = x² - 16x

To complete the square

add ( half the coefficient of the x- term)² to x² - 16x

f(x) = x² + 2(- 8) +(- 8)²

= (x - 8)² + 64

= (x - 8)² ← a perfect square

Answer 2

x=0 or x=16

Explanation:

If

x

2

+

16

x

are the first two terms of an squared expression

(

x

+

a

)

2

=

x

2

+

2

a

x

+

a

2

then

a

=

8

x

2

+

16

x

=

0

can be written as

x

2

+

16

x

+

8

2

=

8

2

#(x+8)^2 = 64

Taking the square root

x

+

8

=

±

8