Question

What are the zeros of the quadratic function f(x)=8^2-16-15

Answer 1

Answer:

C)

Step-by-step explanation:

f(x)=$8x^{2} -16x-15$
$8x^{2} -16x-15=0$
$x=\frac{-b+-\sqrt{b^{2}-4ac } }{2a}$  ,  a=8, b= - 16, c= - 15

$x=\frac{-(-16)+-\sqrt{(-16)^2-4*8*(-15)} }{2*8} = \frac{16+-\sqrt{736} }{16} =\frac{16+-4\sqrt{46} }{16} = 1 +- \frac{\sqrt{46} }{4} = 1+- \frac{\sqrt{23} \sqrt{2}}{2\sqrt{2} \sqrt{2} } =1+-\frac{\sqrt{23} }{2\sqrt{2} } = 1+-\frac{\sqrt{23} }{\sqrt{8} }$