Question 257538
In this case the 1 changes nothing, just ignor it. If it was a -1 then things would change.
2(3x^2-2x+5)+(x^2+3x-7)=2(3x^2-2x+5)+1(x^2+3x-7)
6x^2-4x+10+x^2+3x-7=6x^2-4x+10+x^2+3x-7
7x^2-x+3=7x^2-x+3
everything cancils
=0