Đáp án:
`d, (x + 5)(5x - 3)`
`e, (4x + 7)(8x + 11)`
`f, (-c + a + b)(c - b + a)(c + b - a)(c + b + a)`
Giải thích các bước giải:
`d, (3x + 1)^2 - 4(x - 2)^2`
` = (3x + 1)^2 - ( 2(x - 2) )^2`
` = (3x + 1)^2 - (2x - 4)^2`
` = (3x + 1 - 2x + 4)(3x + 1 + 2x - 4)`
` = (x + 5)(5x - 3)`
`e, 9(2x + 3)^2 - 4(x + 1)^2`
` = ( 3(2x + 3) )^2 - ( 2(x + 1) ) ^2`
` = (6x + 9)^2 - (2x + 2)^2`
` = (6x + 9 - 2x - 2)(6x + 9 + 2x + 2)`
` = (4x + 7)(8x + 11)`
`f, 4b^2c^2 - (b^2 + c^2 - a^2)^2`
` = (2ab)^2 - (b^2 + c^2 - a^2)^2`
` = (2ab - b^2 + c^2 - a^2)(2ab + b^2 - c^2 + a^2)`
` = (-c + a + b)(c - b + a)(c + b - a)(c + b + a)`
