6/7=(6*3)/(7*3)=18/21
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<span>а) (а-в)^2=(в-а)^2</span>
(15ab²+5a²b)-(2a+6b)=5ab(3b+a)-2(a+3b)=(3b+a)(15ab-2)
<span>а) 4p</span>²<span>-( x + y)</span>²=4p²-x²-2xy-y²<span>
б) a</span>²<span>-( b+c) =a</span>²-b-c<span>
в) x-y+x</span>²<span>-2xy+y</span>²=(x-y)+(x-y)²=(x-y)(1+x-y)<span>
г) k</span>²<span>+2mk+m</span>²<span>-k-m=(k+m)</span>²-(k+m)=(k+m)(k+m-1)