SOLUTION: can u solve this problem factorise 15+15x-20x^2

Question 221303: can u solve this problem
factorise
15+15x-20x^2
Answer by drj(1380) (Show Source): You can put this solution on YOUR website!
Can you solve this problem

Factorise

Step 1. Factor out -5 and rearrange in descending order

ANSWER

Step 2. Now work with the terms in the parenthesis. We need two integers m and n whose sum is -3 and whose product m*n=(-3)(4)=-12.

Step 3. After trial and error there are no integers that satisfies the quadratic equation.

Step 4. Use the quadratic formula given below for the equation

where a=4, b=-3, and c=-3

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=57 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 1.31872930440884, -0.568729304408844. Here's your graph:

Step 5. ANSWER: and we could use the quadratic equation to factor out the quadratic terms as found in step 4.

I hope the above steps were helpful.

For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

Good luck in your studies!

Respectfully,
Dr J
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