Question

Write the quadratic function f(x) = x^2 + 8x + 3 in vertex form.

A)f(x) = (x - 4)^2 - 13
B)f(x) = (x - 4)^2 + 3
C)f(x) = (x + 4)^2 + 3
D)f(x) = (x + 4)^2 - 13

Answer 1

when you completed the square you didn't subtract 16

should've been

x^2+8x+16+3-16

Answer 2

so the answer would be D

Answer 3

f'(x) = 2x + 8

2x + 8 = 0

x = -4

f(-4) = (-4)^2+8(-4) +3

f(-4) = 16 + -32 + 3

= -13
Vertex is (-4,-13)
So answer should be D.

Answer 4

moneybird you could have just completed the square instead of using calculus lol

Answer 5

whatever, complete the square is long...