SOLUTION: please help me solve this equation x(x+7)-2=28

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Question 343508: please help me solve this equation x(x+7)-2=28
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
NEED TO KNOW:
TYPE OF EQUATION NEEDED TO USE THE QUADRATIC FORMULA TO SOLVE THE PROBLEM
ax%5E%282%29%2Bbx%2Bc+=0
x(x+7)-2=28
DISTRIBUTE AND SIMPIFY
X%5E%282%29%2B7X-2+=28
X%5E%282%29%2B7X-30+=0
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B7x%2B-30+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%287%29%5E2-4%2A1%2A-30=169.

Discriminant d=169 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-7%2B-sqrt%28+169+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%287%29%2Bsqrt%28+169+%29%29%2F2%5C1+=+3
x%5B2%5D+=+%28-%287%29-sqrt%28+169+%29%29%2F2%5C1+=+-10

Quadratic expression 1x%5E2%2B7x%2B-30 can be factored:
1x%5E2%2B7x%2B-30+=+1%28x-3%29%2A%28x--10%29
Again, the answer is: 3, -10. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B7%2Ax%2B-30+%29