SOLUTION: Solve the equations by a method of your choice. 4x^2+15x+9=0 x^2-8x+16=0 x^2-2x-3=0

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Question 450009: Solve the equations by a method of your choice.
4x^2+15x+9=0
x^2-8x+16=0
x^2-2x-3=0
Found 3 solutions by rwm, stanbon, ewatrrr:
Answer by rwm(914) About Me  (Show Source):
You can put this solution on YOUR website!
one problem at a time
x^2-8x+16=0
factor
factors of 16 which add up to -8
-4 and -4
(x-4)^2=0
x=4

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the equations by a method of your choice.
4x^2+15x+9=0
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Use Inverse-FOIL:
4x^2+12x+3x+9 = 0
4x(x+3)+3(x+3) = 0
(x+3)(4x+3) = 0
x = -3 or x = -3/4
=======================
x^2-8x+16=0
(x-4)^2 = 0
x = 4 with multiplicity 2
=======================
x^2-2x-3=0
(x-3)(x+1) = 0
x = 3 or x = -1
===================
Cheers,
Stan H.
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Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

Using the Quadratic Formula to solve

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

4x^2+15x+9=0   OR 4(x+15/8)^2 = 81/16  x = -15/8  ± 9/8  |Completing square

x+=+%28-15+%2B-+sqrt%28+81+%29%29%2F%288%29+

   x = (-15 ± 9)/8  x = - 3 and x = -6/8 = -3/4

x^2-8x+16=0   OR (x-4)^2 = 0  x = 4  |Completing square

x+=+%288+%2B-+sqrt%280+%29%29%2F%282%29+

   x = 4

x^2-2x-3=0  OR (x-3)(x+1) = 0  x = 3 and x = -1  |Factoring

x+=+%282+%2B-+sqrt%28+16+%29%29%2F%282%29+

   x = (2 ± 4)/2  x = 3 and x = -1