SOLUTION: Factor- 36x^2 - 81 .

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Question 1010182: Factor- 36x^2 - 81 .
Found 3 solutions by MathLover1, Theo, MathTherapy:
Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!





Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
start with 36x^2 - 81 = y
set y = 0 to get 36x^2 - 81 = 0
add 81 to both sides of this equation to get 36x^2 = 81
divide both sides of this equation to get x^2 = 81/36
simplify to get x^2 = 2.25
take the square root of both sides of the equation to get x = 1.5 or x = -1.5

this is also in the form of (a^2 - b^2) = (a + b) * (a - b)

a^2 = 36x^2 so a = 6x
b^2 = 81 so b = 9

you get (36x^2 - 81) = ((6x)^2 - 9^2) = (6x + 9) * (6x - 9)

set each of these factors equal to 0 and you get 6x = -9 and 6x = 9

solve for x in each to get x = -1.5 and x = 1.5

you could also have used the quadratic formula which would have gotten you the same answer.

the equation of 36x^2 - 81 = 0 yields:
a = 36
b = 0
c = -81

the quadratic formula is x = (-b plus or minus sqrt(b^2-4ac)) divided by 2a.

solve it and you will see that x = plus or minus 1.5.





Answer by MathTherapy(10557)   (Show Source): You can put this solution on YOUR website!

Factor- 36x^2 - 81 .
Difference of 2 squares:  

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