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ginny1029
05-31-2009, 01:06 PM
the instructions are solve by completing the square

the problem reads

2x^2 + 6x -56 = 0

i divide everything by 2 to get the x by itself and move the -56

2x^/2 + 6x/2_______ = 56/2

i now have
x^2 + 3x _______ = 28

i divide the 3 by 1/2 and get 3/2 and square it and get 9/4

x^2 + 3x + 9/4 = 28 + 9/4

i change the 28 to fourths and get

x^2 + 3x + 9/4 = 112/4 + 9/4

x^2 + 3x + 9/4 = 121/4

this becomes

(x + 3/2)^2 = 121/4

does this look right so far?

Loren
05-31-2009, 02:39 PM
Looks good to me. Keep going.

ginny1029
05-31-2009, 03:26 PM
ok so i have (x + 3/2) ^2 = 121/4

now i go

x + 3/2 = plus or minus the square root of 121/4

x = -3/2 plus or minus the square root of 121/4

put im not sure were to go from there exactly do i need to simplify more?

stapel
05-31-2009, 04:35 PM
What is the square root of 121? :wink:

Then combine the fractions....

ginny1029
05-31-2009, 05:42 PM
Thank you!!