\(3x-4x^2+7=-\left(4x^2-3x-7\right)=-\left(x+1\right)\left(4x-7\right)\)
3x-4x2+7
=-4x2+3x+7
=-4x2-4x+7x+7
=-(4x2+4x)+(7x+7)
=-4x(x+1)+7(x+1)
=(x+1)(-4x+7)
\(3x-4x^2+7\)
\(=4x^2-4x+7x-7\)
\(=-\left(4x^2+4x\right)+\left(7x+7\right)\)
\(=-4x\left(x+1\right)7\left(x+1\right)\)
\(=\left(4x+7\right)\left(x+1\right)\)