Form the quadratic equation whose roots are the squares of the sum of the roots and square of the difference of the root of the equation 2x^2+2(m+n)x+m^2+n^2=02x2+2(m+n)x+m2+n2=0.?

1 Answer
Jun 1, 2016

Desired equation is x^2-4mnx-(m^2-n^2)^2=0x24mnx(m2n2)2=0

Explanation:

Let alphaα and betaβ be the roots of the equation 2x^2+2(m+n)x+m^2+n^2=02x2+2(m+n)x+m2+n2=0

As such alpha+beta=-2(m+n)/2=-(m+n)α+β=2m+n2=(m+n)

and alphaxxbeta=(m^2+n^2)/2α×β=m2+n22

We have to find the equation whose roots are (alpha+beta)^2(α+β)2 and (alpha-beta)^2(αβ)2.

Sum of these roots will be (alpha+beta)^2+(alpha-beta)^2=2(alpha^2+beta^2)(α+β)2+(αβ)2=2(α2+β2)

= 2((alpha+beta)^2-2alphabeta)=2((-(m+n))^2-2(m^2+n^2)/2)2((α+β)22αβ)=2(((m+n))22m2+n22)

= 2(m+n)^2-2(m^2+n^2)=4mn2(m+n)22(m2+n2)=4mn

Product of these roots will be (alpha+beta)^2xx(alpha-beta)^2(α+β)2×(αβ)2

= (alpha^2-beta^2)^2=(alpha^2+beta^2)^2-4alpha^2beta^2(α2β2)2=(α2+β2)24α2β2

= ((alpha+beta)^2-2alphabeta)^2-4alpha^2beta^2((α+β)22αβ)24α2β2

= ((-m-n)^2-2(m^2+n^2)/2)^2-4((m^2+n^2)/2)^2((mn)22m2+n22)24(m2+n22)2

= 4m^2n^2-m^4-n^4-2m^2n^2=-m^4-n^4+2m^2n^24m2n2m4n42m2n2=m4n4+2m2n2

= -(m^2-n^2)^2(m2n2)2

Hence equation will be

x^2-x2(sum of roots)x+x+product of roots=0=0 or

x^2-4mnx-(m^2-n^2)^2=0x24mnx(m2n2)2=0