Question

-x^2+16x+64=0 need to know using quadratic formula to find the zeroes

Answer 1

`x= 8\left(1- \sqrt 2 \right)\\\\\\x= 8\left(1+ \sqrt 2 \right)\\`

Step by step explanation:

`-x^2 +16x +64 =0\\\\\text{Use the quadratic equation formula,}~~ x = (-b\pm√(b^2-4ac))/(2a)\\\\\text{In this case,}~ a=-1, b=16, c=64\\\\\\x=(-16\pm√(16^2 -4 \cdot (-1)(64)))/(2(-1))\\\\\\~~~=(-16\pm√(512))/(-2)\\\\\\~~~=(-16 \pm √(256 * 2))/(-2)\\\\\\~~~=(-16 \pm 16\sqrt2)/(-2)\\\\\\~~~=8 \pm(-8)\sqrt 2\\\\\text{Hence,}\\\\x=8-8\sqrt 2 = 8\left(1- \sqrt 2 \right)\\\\x= 8+8\sqrt 2 = 8\left(1+ \sqrt 2 \right)`