How do you factor $5 a^{2} + 10 a b - 40 b^{2}$ $5a^2 + 10ab - 40b^2$ ?

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Answer 1 · 2015-09-10T19:40:01

One way of doing it is in the explanation

Hence we have that

$5a^2+10ab-40b^2=> 5(a^2+2ab+b^2)-45b^2=> 5(a+b)^2-(sqrt45b)^2=> (sqrt5(a+b))^2-(sqrt45*b)^2=> (sqrt5*(a+b)+sqrt45*b))*(sqrt5*(a+b)-sqrt45b)$

Or noticing that $sqrt(45)=sqrt(9*5)=3*sqrt5$

we get that

$5a^2+10ab-40b^2=5*(a+4b)*(a-2b)$

How do you factor 5a^2 + 10ab - 40b^25a2+10ab−40b25a^2 + 10ab - 40b^2?