How do you factor #42x^2 + 5xy - 25y^2#?

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Answer 1 · 2018-04-08T01:42:51

#(6x-5)(7x+5)#

#(6x-5)(7x+5)#

You can use the quadratic formula or the cross-multiply rule (i think that's what it's called)

Quadratic formula = #(-b+-sqrt(b^2-4ac))/(2a)#

#a=42,b=5,c=-25#

#x=(-5+-sqrt(5^2-4*42*-25))/(2*42)#

#x=(-5+-sqrt(4225))/84#

#x=(-5+-65)/84#

#x=-70/84=-5/6# or #x=60/84=5/7#

So your equation is

#(x-5/6)(x+5/7)#

=#(6x-5)(7x+5)#