Factorize:7x2+49x+84
We have: 7x2+49x+84=7(x2+7x+12)We now have to split 7 into two numbers such that their sum is 7 and their product is 12.Clearly, 3+4=7 and 3×4=12.∴7x2+49x+84
=7(x2+7x+12)
=7(x2+4x+3x+12)
=7[x(x+4)+3(x+4)]
=7(x+4)(x+3)
Which of the following is a factor of (49x2−1)+(1+7x)2?