Question

What value of b makes the polynomial below a perfect square?

x2 + bx + 16

b =

A. 16
B. 8
C. 2
D. 4

Answer 1

(x + 4)^2 = x2 + bx + 16
Solve for b.

Answer 2

\(\Large \color{MidnightBlue}{\Rightarrow (x + 4)^2 }\)

This is the value, clearly, as (x + 4)^2 will be x^2 + 16 + 2*4*x

Answer 3

x^2 + 8x + 16 = x^2 + bx + 16
So b is 8.

Answer 4

\(\Large \color{MidnightBlue}{\Rightarrow (a + b)^2 = a^2 + 2a + b^2 }\)