SOLUTION: Determine the solutions for the following polynomial equation. (2x+6)^2 =36

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Question 98965: Determine the solutions for the following polynomial equation.
(2x+6)^2 =36

Answer by doukungfoo(195) About Me  (Show Source):
You can put this solution on YOUR website!
This problem can be solved by using the quadratic formula
which is x=-b%2B-sqrt%28b%5E2-4ac%29%2F2a
but first it needs to be be simplified to the proper format ax%5E2%2Bbx%2Bc=0
%282x%2B6%29%5E2=36
first expand %282x%2B6%29%5E2
%282x%2B6%29%282x%2B6%29=36
Now multply %282x%2B6%29%282x%2B6%29 using the FOIL method
so
%282x%2B6%29%282x%2B6%29=36 becomes
4x%5E2%2B12x%2B12x%2B36=36
Now simplify by combining like terms
4x%5E2%2B24x%2B36=36
Next you want to set the equation equal to zero so that it will be in the proper format to use the quadratic formula
So subtract 36 from both sides of the equal sign
4x%5E2%2B24x%2B36-36=36-36
now we have
4x%5E2%2B24x%2B0=0 compare it to this:
ax%5E2%2Bbx%2Bc=0 you can see that the a is represented by the number 4
the b is the number 24 and c is the number zero.
Now you are ready to use the quadratic formula to solve for x
x=-b%2B-sqrt%28b%5E2-4ac%29%2F2a
Just replace a,b, and c with the correct number. In this problem a=4, b=24, and c=0 so now the formula looks like this:
x=-24%2B-sqrt%2824%5E2-4%284%29%280%29%29%2F2%284%29
next just do the math, remembering to follow order of operations.
x=%28-24%2B-sqrt%28576%29%29%2F8
At this point you need to split the equation into two seperate equations. This is done because of the +- This is how we get two answers when solving for x.
So now we have:
x=%28-24%2Bsqrt%28576%29%29%2F8 and x=%28-24-sqrt%28576%29%29%2F8
The squareroot of 576 is 24 so now we have this:
x=%28-24%2B24%29%2F8 and x=%28-24-24%29%2F8
x=%280%29%2F8 and x=%28-48%29%2F8
x=0 and x=-6
So finally we get our answers and remember with a quadratic equation you should always get two answers. To check them just plug them back in to the original problem %282x%2B6%29%5E2=36