Question

change the quadratic function to standard form
y=3(x+2)(x-5)

Answer 1

http://sketchtoy.com/39965130

Answer 2

you have to multiply the monoms x=2 and x-5 let see:
\[y=3(x*x-5*x+2*x+2*(-5))=3(x^2-5x+2x-10)=3(x^2-3x-10)=3x^2-9x-30\]

Answer 3

sorry missed the final though:
\[3x^2-9x-30\]