Đáp án:
Giải thích các bước giải:
a) (2x + 1) 2 +(2x + 3) 2 – 2(2x + 1)(2x + 3)
= 2[(2x+1) + (2x+3) - (2x +1)(2x+3)]
=2[2x + 1 + 2x + 3 - (4x² + 8x + 3)]
= 2( 4x + 4 - 4x² - 8x - 3)
= 2(-4x² -4x + 1)
= -8x² - 8x + 1
b) (2x – 3)(2x + 3) – (x + 5) 2 – (x – 1)(x + 2)
= 4x² - 9 - (2x + 10) - (x² + x - 2)
= 4x² - 9 - 2x -10 - x² - x + 2
= 3x² -3x - 17
c) (24x²y² z² – 12x³y²z³ + 36x²y²z²) : (-6x²y²z² )
= (60x²y²z² - 12x³y²z³) : (-6x²y²z² )
= 60x²y²z² : -6x²y²z² - 12x³y²z³ : -6x²y²z²
= -10 + 2xz
d) (x + 2y)(x² – 2xy + 4y² ) – (x – y)(x² + xy + y² )
= x³ -2x²y + 4xy² + 2x²y -2xy² + 8y³ - (x³ + x²y + xy² - x²y -xy² - y³)
= x³ -2x²y + 4xy² + 2x²y -2xy² + 8y³ - x³ - x²y - xy² + x²y + xy² + y³
= 9y³ -2xy²