Question

分解因式（1）a^2(x（5）已知m,n为自然数,且m(m-n)-n(n-m)=13,求m,n的值（6）已知a-b=-4

Answer 1

(5) m(m-n)-n(n-m)=m(m-n)+n(m-n)=(m-n)(m+n)=13=1*13

=> m-n=1;m+n=13 =>相加 2m=14 =>m=7,n=6

(6) a^2+b^2 =(a-b)^2+2ab=4^2+2*3=16+6=22

-3a^3b+6a^2b^2-3ab^3=-3ab(a^2+b^2) +6(ab)^2=-3*3*22+6*3^2=-198+54= - 144

(7)x+3y=-2 => x^2+3xy-6y=x(x+3y)-6y =x(-2)-6y =-2x-6y=-2(x+3y)=-2*(-2)=4

(8) -2x^1+ax-12=(2x-3)(-x+4) = -2x^2+11x-12 => a=11

因式分解 -(2x-3)(x-4)