a) (x + 1) (x - 2)
= x2 - 2x + x - 2
b) - 7x2 . (3x - 4y)
= - 21x3 + 28x2y
c)(x + 4) (x - 2) (x - 3)2
= (x2 - 2x + 4x - 2 ) (x2 - 2.x.3 + 32)
= x2 - 2x + 4x - 2 + x2 - 6x + 9
= - 4x + 9
2 a) (x + 2y)2 = x2 + 2.x.2y + (2y)2 = x2 + 4xy + 4y2
b)(x - 2y)2 = x2 - 2.x.2y + (2y)2 = x2 - 4xy + 4y2
a) (x + 1)(x - 2)
= x² - 2x + x - 2
= x² - x - 2
b) -7x²(3x - 4y)
= -21x³ + 28x²y
c) (x + 4)(x - 2)(x - 3)²
= (x² - 2x + 4x - 8)(x² - 6x + 9)
= (x² + 2x - 8)(x² - 6x + 9)
= x⁴ - 6x³ + 9x² + 2x³ - 12x² + 18x - 8x² + 48x - 72
= x⁴ - 4x³ - 11x² + 66x - 72
