Question

Select the approximate values of x that are solutions to f(x) = 0, where 

f(x) = -8x^2 + 8x + 5.

Answer 1

`f(x)=-8x^2+8x+5\\\\f(x)=0\iff-8x^2+8x+5=0\\\\a=-8;\ b=8;\ c=5\\\\\Delta=b^2-4ac\\\\\Delta=8^2-4\cdot(-8)\cdot5=64+160=224\\\\x_1=(-b-\sqrt\Delta)/(2a);\ x_2=(-b+\sqrt\Delta)/(2a)\\\\\sqrt\Delta=√(224)\approx√(225)=15\\\\x_1\approx(-8-15)/(2\cdot(-8))=(-23)/(-16)=1(7)/(16)\approx1.5\\\\x_2\approx(-8+15)/(2\cdot(-8))=(7)/(-16)=-(7)/(16)\approx-0.5`