Factor 5x^2-18x-8

Problem

5*x2−18*x−8

Solution

1. Identify the coefficients of the quadratic expression a*x2+b*x+c where a=5 b=−18 and c=−8

2. Find two numbers that multiply to a⋅c=5⋅(−8)=−40 and add to b=−18

3. Determine the pair of numbers, which are −20 and 2

4. Rewrite the middle term −18*x using the two numbers found: −20*x+2*x

5*x2−20*x+2*x−8

5. Factor by grouping by taking the greatest common factor out of the first two terms and the last two terms.

5*x*(x−4)+2*(x−4)

6. Factor out the common binomial (x−4)

(5*x+2)*(x−4)

Final Answer

5*x2−18*x−8=(5*x+2)*(x−4)

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