Question

Rút gọn biểu thức

a, 3(x-y)^2 - 2(x+y)^2 - (x-y)(x+y)

b, 2(2x+5)^2 - 3(4x+1)(1-4x)

Answer 1

a. 3(x - y)² - 2(x + y)² - (x - y)(x + y)

= 3(x² - 2xy + y²) - 2(x² + 2xy + y²) - (x² - y²)

= 3x² - 6xy + 3y² - 2x² - 4xy - 2y² - x² + y²

= - 10xy + 2y²

b. 2(2x + 5)² - 3(4x + 1)(1 - 4x)

= 2(4x² + 20x + 25) - 3(1 + 4x)(1 - 4x)

= 8x² + 40x + 50 - 3(1 - 16x²)

= 8x² + 40x + 50 - 3 + 48x²

= 56x² + 40x + 47

pn coi kt lại nhé

Answer 2

a) \(3(x-y)^2 - 2(x+y)^2 - (x-y)(x+y)\)

\(= 3(x^2 - 2xy + y^2) - 2 (x^2 +2xy+y^2) - (x^2 - y^2)\)

\(=\) \(3x^2 - 6xy + 3y^2 - 2x^2 - 4xy - 2y^2 - x^2 - y^2\)

\(= -10 xy - 3y^2\)