Question

Fie a,b,x,y €R ,astfel incat 3a-2b=12 si x-y=5.Calculati:a)x(3a-2b)+y(2b-3a) b)a(3x-3y)-2(bc-by)+10​

Answer 1

$3a-2b=12\\2b-3a=-12\\x-y=5\\x(3a-2b)+y(2b-3a)=12x-12y=12(x-y)=12\cdot5=60\\a(3x-3y)-2(bx-by)+10=3a(x-y)-2b(x-y)+10=5\cdot3a-5\cdot2b+10=5(3a-2b)+10=5\cdot12+10=70$