roots of -4x^2+80x-100
Solve for x:
-(4 x^2)+80 x-100 = 0
Divide both sides by -4:
x^2-20 x+25 = 0
Subtract 25 from both sides:
x^2-20 x = -25
Add 100 to both sides:
x^2-20 x+100 = 75
Write the left hand side as a square:
(x-10)^2 = 75
Take the square root of both sides:
x-10 = 5 sqrt(3) or x-10 = -5 sqrt(3)
Add 10 to both sides:
x = 10+5 sqrt(3) or x-10 = -5 sqrt(3)
Add 10 to both sides:
Answer: | x = 10+5 sqrt(3) or x = 10-5 sqrt(3)
