(6х+5)²-9=(6х+5-3)(6х+5+3)=(6х+2)(6х+8)=2(3х+1)*2(3х+4)=2*2(3х+1)(3х+4)=4(3х+1)(3х+4)
4(3х+1)(3х+4) - кратно 4
(6х+5)²-9=(6х+5-3)(6х+5+3)=(6х+2)(6х+8)=2(3х+1)*2(3х+4)=2*2(3х+1)(3х+4)=4(3х+1)(3х+4)
4(3х+1)(3х+4) - кратно 4