Răspuns :
a) 2x-2+5x-5=7x-7
b) ax-2x+5a-10+ax+x+5a+5=2ax+10a-x-5
c) 6xy+8x-21y-28+4xy-4x-14y+14=10xy-4x-35y-14
b) ax-2x+5a-10+ax+x+5a+5=2ax+10a-x-5
c) 6xy+8x-21y-28+4xy-4x-14y+14=10xy-4x-35y-14
[tex]2(x-1)+5(x-1) = 2x-2+5x-5=7x-7=7(x-1)[/tex]
[tex](x+5)(a-2)+(x+5)(a+1)= xa-2x+5x-10+xa+x+5x+5[/tex][tex][tex](2x-7)(3y+4)+(2x-7)(2y-2)= 6xy+12x-21y-28+(4xy[/tex][tex] 6xy+8x-21y-28+4xy-4x-14y+14=10xy+12x-35y-14[/tex]= 2xa+9x-5[/tex]
[tex](x+5)(a-2)+(x+5)(a+1)= xa-2x+5x-10+xa+x+5x+5[/tex][tex][tex](2x-7)(3y+4)+(2x-7)(2y-2)= 6xy+12x-21y-28+(4xy[/tex][tex] 6xy+8x-21y-28+4xy-4x-14y+14=10xy+12x-35y-14[/tex]= 2xa+9x-5[/tex]