Question 368736
{{{15(2x+1)^3+6(2x+1)^2-21(2x+1)}}}
={{{3(2x+1)*(5(2x+1)^2+2(2x+1)-7)}}}
={{{3(2x+1)(5(2x+1)+7)((2x+1)-1)}}}
={{{3(2x+1)(10x+5+7)(2x+1-1)}}}
={{{3(2x+1)(10x+12)(2x)}}}
={{{6x(2x+1)2(5x+6)}}}
={{{12x(2x+1)(5x+6)}}}.