For which value of $x$ does $4 x ^ { 2 } - 10 x + 15$ reach a minimum? Restrict your attention to the horizontal span of 0 to 10.
A) 15
B) 8.75
C) 1.25
D) 0

Question

Quizplus · Accepted Answer

The minimum value of a quadratic function $ax^2 + bx + c$ occurs at $x = -\frac{b}{2a}$. For the given function $4x^2 - 10x + 15$, $a = 4$ and $b = -10$, so the minimum occurs at $x = -\frac{-10}{2*4} = \frac{10}{8} = 1.25$.

For Which Value Of xxx Does 4x2−10x+154 x ^ { 2 } - 10 x + 154x2−10x+15

For Which Value Of $x$ Does $4 x ^ { 2 } - 10 x + 15$