Question

explain how a trinomial of the form 2x2 + 13x + 15 can be turned into a four term polynomial suitable for factoring by grouping

Answer 1

i think it goes like this, but myininaya is the expert.
multiply 2 by 15 get 30.
then think of two numbers whose product is 30 and that add to 13
not too hard, we get 10 and 3
then write
\[2x^2+10x+3x+15\] and factor

Answer 2

factor the first as
\[2x(x+5)\] and second as
\[3(x+5)\] so you get
\[2x(x+5)+3(x+5)=(2x+3)(x+5)\]