Toán Tính: a)(x+3)^2 b)(3x+4y)^2 c)(1/2 -3y)^2 d)-(x-3y)^2 e)-(4x – 5y)^2 24/07/2021 By Gianna Tính: a)(x+3)^2 b)(3x+4y)^2 c)(1/2 -3y)^2 d)-(x-3y)^2 e)-(4x – 5y)^2
a, (x+3)² = x² + 2.x.3 + 3² = x² + 6x + 9 b, ( 3x + 4y)² = 3x² + 2. 3x. 4y + 4y² = 3x² + 24xy + 4y² c, ($\frac{1}{2}$ – 3y)² = $\frac{1}{2}$ ² – 2. $\frac{1}{2}$ . 3y + 3y² = $\frac{1}{4}$ ² – 3y + 3y² d, -(x – 3y)² = (x + 3y) ² = x² + 6xy + 3y² e, -( 4x – 5y)² = (4x + 5y)² =4x² + 40xy + 5y² Trả lời