Đáp án:
`1, (x - 4y)^2 = x^2 - 2.x.4y + (4y)^2`
`= x^2 - 8xy + 16y^2`
`2, (3 - xy)^2 = 3^2 - 2.3.xy + (xy)^2`
`= 9 - 6xy + x^2.y^2`
`3, (3x - 1/y)^2 = (3x)^2 - 2.3x.(1/y) + (1/y)^2`
`= 9x^2 - (6x)/y + 1/y^2`
`4, (2x - 3)^2 = (2x)^2 - 2.2x.3 + 3^2`
`= 4x^2 - 12x + 9`
`5, (2/x - 5y)^2 = (2/x)^2 - 2.(2/x).5y + (5y)^2`
`= 4/x^2 - (20y)/x + 25y^2`
`6, (4x - 3)^2 = (4x)^2 - 2.4x.3 + 3^2`
`= 16x^2 - 24x + 9`
`7, (3 - 2x)^2 = 3^2 - 2.3.2x + (2x)^2`
`= 9 - 12x + 4x^2`
`8, (x^2 - 3x)^2 = (x^2)^2 - 2.x^2 .3x + (3x)^2`
`= x^4 - 6x^3 + 9x^2`
`9, (x - 2/y)^2 = x^2 - 2.x.(2/y) + (2/y)^2`
`= x^2 - (4x)/y + 4/y^2`
`10, (3x - 2y)^2 = (3x)^2 - 2.3x.2y + (2y)^2`
`= 9x^2 - 12xy + 4y^2`
Học tốt
