Question

a) (2x + 1)² - 49x² + 56x - 16

b) x^m+4 - x^m+3 - x - 1

Answer 1

a) \(\left(2x+1\right)^2-49x^2+56x-16\)

\(=4x^2+4x+1-49x^2+56x-16\)

\(=-45x^2+60x-15\)

\(=-45x^2+45x+15x-15\)

\(=-45x\left(x-1\right)+15\left(x-1\right)\)

\(=\left(-45x+15\right)\left(x-1\right)\)

\(=-15\left(3x-1\right)\left(x-1\right).\)

Answer 2

câu b sai đề

Answer 3

1.a) \(\left(2x+1\right)^2-49x^2+56x-16\)

\(=\left(2x+1\right)^2-\left[\left(7x\right)^2-2.8.7x-4^2\right]\)

\(=\left(2x+1\right)^2-\left(7x-4\right)^2\)

\(=\left(2x+1+7x-4\right)\left(2x+1-7x+4\right)\)

\(=\left(9x-3\right)\left(5-5x\right)\)