2x-y=2
<span>3x-y=15 у=3х-15 у=3х-15 у=3х-15 у=3х-15 у=-6</span>
<span>6x+y=12 6х+у=12 6х+3х-15=12 9х=27 х=3 х=3</span>
=(ab-4b)+(-ac+4c)=b(a-4)-c(a-4)=(b-c)(a-4)