Question

己知m+n=3 mn=2 求:3m+3n一4mn的值和 5(m+2n一mn)一2(m+3n一1)+M的值

Answer 1

3m+3n-4mn=3(m+n)-4mn=3×3-4×2=1

5(m+2n-mn)-(2m+3n-1)+m

=5m+10n-5mn-2m-6n+2+m

=4m+4n-5mn

=4(m+n)-5mn

=4×3－5×2

=2