1)
3x(x · 4y) − 2x(x − 4y)
=12x2y−2x2+8xy
2)
−(2a − 3b)² − (2b − 3a)²
= −(4a2−12ab+9b2)−(4b2−12ab+9a2)
=−4a2+12ab−9b2−4b2+12ab−9a2
=−13a2+24ab−13b2
3)
\( \Large{\frac{(x−4)(3x−1)}{(2x^2+7x−9) · (2x + 1)}} \)
=\( \Large{\frac{3x^2−x−12x+4}{4x^3+2x^2+14x^2+7x−18x−9}}\)
=\( \Large{\frac{3x^2−13x+4}{4x^3+16x^2−11x−9}}\)