If α,β are roots of the equation x2+lx+m=0, write an equation whose roots are −1α and −1β.
α and β are the roots x2+lx+m=0,...(i)
∴α+β=−ba=1and αβ=ca=mNow,The quadratic equation whose roots are−1α and 1β is x2−(sum of roots) x+(product of roots)=0⇒x2−(−1α+−1β)+(−1α,−1β)=0⇒x2+(α+βαβ)x+1αβ=0⇒x2+(−1m)x+1m=0⇒mx2−lx+1=0