Bài `1:`
`a, (x + 2)^2 = x^2 + 2. x. 2 + 2^2 = x^2 + 4x + 4`
`b, (x - 1)^2 = x^2 - 2. x. 1 + 1^2 = x^2 - 2x + 1`
`c, (x^2 + y^2)^2 = (x^2)^2 + 2. x^2. y^2 + (y^2)^2 = x^4 + 2x^2y^2 + y^4`
`d, (x^3 + 2y^2)^2 = (x^3)^2 + 2. x^3. 2y^2 + (2y^2)^2 = x^6 + 4x^3y^2 + 4y^4`
`e, (x^2 - y^2)^2 = (x^2)^2 - 2. x^2. y^2 + (y^2)^2 = x^4 - 2x^2y^2 + y^4`
`f, (x - y^2)^2 = x^2 - 2. x. y^2 + (y^2)^2 = x^2 - 2xy^2 + y^4`
Bài `2:`
`a, x^2 + 4x + 4 = x^2 + 2. x. 2 + 2^2 = (x + 2)^2`
`b, x^2 - 8x + 16 = x^2 - 2. x. 4 + 4^2 = (x - 4)^2`
`c, (x + 5)(x - 5) = x^2 - 5^2 = x^2 - 25`
`d, x^2 + 2x + 1 = x^2 + 2. x. 1 + 1^2 = (x + 1)^2`
`e, 4x^2 - 9 = (2x)^2 - 3^2 = (2x - 3)(2x + 3)`
`f, (2 + bx^2)(bx^2 - 2) = (bx^2+ 2)(bx^2 - 2) = (bx^2)^2 - 2^2 = b^2x^4 - 4`
`f, (2x + 3y)^2 + 2(2x + 3y) + 1 = (2x + 3y)^2 + 2. (2x + 3y). 1 + 1^2 = [(2x + 3y) + 1]^2`
