SOLUTION: How do I solve this algebra problem? solve x(x-8)= -15

Question 214177: How do I solve this algebra problem?
solve x(x-8)= -15
Found 3 solutions by Alan3354, jim_thompson5910, drj:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
x(x-8)= -15

(x-5)*(x-3) = 0
x=5, x=3

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Start with the given equation

Distribute

Add 15 to both sides.

Notice we have a quadratic in the form of where , , and

Let's use the quadratic formula to solve for x

Start with the quadratic formula

Plug in , , and

Negate to get .

Square to get .

Multiply to get

Subtract from to get

Multiply and to get .

Take the square root of to get .

or Break up the expression.

or Combine like terms.

or Simplify.

So the answers are or
Answer by drj(1380)   (Show Source): You can put this solution on YOUR website!
How do I solve this algebra problem?
solve

Step 1. Multiply and simplify

Step 2. Add 15 to both sides to get a quadratic equation

Step 3. Factor as follows

Then and

and ANSWER
We can also use the quadratic formula

where a=1, b=-8 and c=15

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=4 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 5, 3. Here's your graph:

Based on the above steps using the quadratic formula, we have x=5 and x=3...same as before.

I hope the above steps were helpful.

For free Step-By-Step Videos on Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra or for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

And good luck in your studies!

Respectfully,
Dr J
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