Question

Find the extreme value of the quadratic function y = x2 + 4x – 5.

Answer 1

Step-by-step explanation:

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Answer 2

Step-by-step explanation:

The extreme value of any quadratic function

$y = a {x}^{2} + bx + c$

is given by:

$- \frac{d}{4a}$

where

$d = {b}^{2} - 4ac$

In given question

$y = {x}^{2} + 4x - 5$

$a = 1 \\ b = 4\\ c = - 5$

therefore

$d = {4}^{2} - 4 \times 1 \times - 5$

$d = 16 + 20 = 36$

Therefore extreme value:

$-36 \div (4 \times 1) = -9$