My name is Kimmy, and i don't know how to factor the trinomial 25y2 + 20yz - 4z2. I can get it, but i get messed up on getting the minus 4 at the end. all i get is a plus 4. Can it even be factored. I am a student and i am in Highschool algebra 1


Hi Kimmy,

You are correct about the minus 4 creating a problem. If the problem were

25y2 + 20yz + 4z2 then it would factor as (5y + 2)2

Consider the equation

a y2 + b y + c = 0 where a = 25, b = 20 z and c = -4 z2. If the expression 25y2 + 20yz - 4z2 factors, then the equation above has roots that are rational expressions. Use the general quadratic to solve a y2 + b y + c = 0 Are the roots rational?

Go to Math Central