Question

已知方程x²+mx+n=0的两个根为3和-4,则代数式x2+mx+n可分解为

Answer 1

x1+x2=-m

∴-m=3+(-4)=-1

m=1

x1·x2=n=3×(-4)=-12

x^2+mx+n

=x^2+x-12

=(x+4)(x-3)