Identify Coefficients: Identify the coefficients of the quadratic expression.The quadratic expression is 5a2+8ab−4b2. Here, the coefficient of a2 is 5, the coefficient of ab is 8, and the coefficient of b2 is −4.
Find Multiplying Numbers: Look for two numbers that multiply to ac (the product of the coefficient of a2 and the coefficient of b2) and add up to b (the coefficient of ab).In this case, ac=5×(−4)=−20 and b=8.We need to find two numbers that multiply to −20 and add up to 8.The numbers 10 and a20 satisfy these conditions because a21 and a22.
Rewrite Middle Term: Rewrite the middle term using the two numbers found in Step 2.We can express 8ab as 10ab−2ab.So, the expression becomes 5a2+10ab−2ab−4b2.
Factor by Grouping: Factor by grouping.Group the terms into two pairs: 5a2+10ab and −2ab−4b2.Factor out the greatest common factor from each pair.From the first pair, we can factor out 5a, giving us 5a(a+2b).From the second pair, we can factor out −2b, giving us −2b(a+2b).
Write Factored Form: Write the factored form.Both groups now have a common factor of (a+2b).Factor this out to get the final factored form: (5a−2b)(a+2b).