+109 4x^2 - 24x + 31 = 0 solve by completing the square?
A.) -3 + square root of 5/4, x=-3 - square root of 5/4
B.) x= 3 + square root of 5/4, x= 3 - square root of 5/4
C.) 1+ square root of 3/2, 1- square root of 3/2
D.) x= -1 + square root of 3, -1 - square root of 3
Solve for x:
4 x^2-24 x+31 = 0
Divide both sides by 4:
x^2-6 x+31/4 = 0
Subtract 31/4 from both sides:
x^2-6 x = -31/4
Add 9 to both sides:
x^2-6 x+9 = 5/4
Write the left hand side as a square:
(x-3)^2 = 5/4
Take the square root of both sides:
x-3 = sqrt(5)/2 or x-3 = -sqrt(5)/2
Add 3 to both sides:
x = 3+sqrt(5)/2 or x-3 = -sqrt(5)/2
Add 3 to both sides:
Answer: | x = 3+sqrt(5)/2 or x = 3-sqrt(5)/2
