(6х)^2-9^2=(6х-9)*(6х+9)=3(2х-3)*3(2х+3)= 9(2х-3)(2х+3)=0
х=1,5 или х=-1,5
1) (2a²-3b)(a²+2ab+5b²)=2a⁴+4a³b+10a²b²-3a²b-6ab²-15b³
2) (x²-2xy)(x²-5xy+3y²)=x⁴-5x³y+3x²y²-2x³y+10x²y²-6xy³=x⁴-7xy+13x²²y²-6xy³
3) (x-y)(x³+x²y+xy²+y³)=x⁴+x³y+x²y²+xy³-x³y-x²y²-xy³-y⁴=x⁴-y⁴
4) (a+b)(a³-a²b+ab²-b³)=a⁴-a³b+a²b²-ab³+a³b-a²b²+ab³-b⁴=a⁴-b⁴
5) (5a-4b)(a³+2a²b-5ab²-3b³)=5a⁴+10a³b-25a²b²-15ab³-4a³b-8a²b²+20ab³+12b⁴=5a⁴+6a³b-33a²b²+5ab³+12b⁴
6) (2x+3y)(x³+3x²y-3xy²+4y³)=2x⁴+6x³y-6x²y²+8xy³+3x³y+9x²y²-9xy³+12y⁴=2x⁴+9x³y+3x²y²-xy³+12y⁴