Đáp án:
`=(3x+1)(6x+5)(48x^2+56x+19)`
Giải thích các bước giải:
`A=(12x+7)^2.(3x+2).(2x+1)-3`
`=(144x^2+168x+49)(6x^2+7x+2)-3`
`=>24A=(144x^2+168x+49)(144x^2+168x+48)-72`
`=>96A=(288x^2+336x+98)(288x^2+336x+96)-288`
`=>96A=(288x^2+336x+97+1)(288x^2+336x+97-1)-288`
`=>96A=(288x^2+336x+97)^2-289`
`=>96A=(288x^2+336x+80)(288x^2+336x+114)`
`=>96A=(16.18x^2+16.21x+16.5)(6.48x^2+6.56x+19.6)`
`=>96A=16.6(18x^2+21x+5)(48x^2+56x+19)`
`=>A=(18x^2+21x+5)(48x^2+56x+19)`
`=>A=(18x^2+6x+15x+5)(48x^2+56x+19)`
`=>A=[6x(3x+1)+5(3x+1)](48x^2+56x+19)`
`=>A=(3x+1)(6x+5)(48x^2+56x+19)`
