SOLUTION: solve by factoring: 16x^2 - 81 = 0 solve by completing the square: 6x - 2 = x^2 solve by the quadratic formula: 8x + 4 = 2x^2 (PS: Please show how you worked it o

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: solve by factoring: 16x^2 - 81 = 0 solve by completing the square: 6x - 2 = x^2 solve by the quadratic formula: 8x + 4 = 2x^2 (PS: Please show how you worked it o      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 142864: solve by factoring:
16x^2 - 81 = 0

solve by completing the square:
6x - 2 = x^2

solve by the quadratic formula:
8x + 4 = 2x^2

(PS: Please show how you worked it out. I have been having mojor problems with these kinds of questions. Thanks.)
Answer by nabla(475) About Me  (Show Source):
You can put this solution on YOUR website!
16x^2 - 81 = 0
(4x+9)(4x-9)=0
x= +/- (9/4)
.
.
.
6x - 2 = x^2
0=x^2-6x+2
0=x^2-6x+9+2-9
7=(x-3)^2
+-sqrt(7)=x-3
3%2B-sqrt%287%29=x
.
.
.
8x + 4 = 2x^2
0=2x^2-8x-4
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%288+%2B-+sqrt%28+64-4%2A2%2A%28-4%29+%29%29%2F%282%2A2%29+
x+=+%288+%2B-+sqrt%28+96+%29%29%2F%284%29+
x=2 +/- 4sqrt(6)/4
x=2 +/- sqrt(6)