Question

solve by the method of cross multiplication m x minus ny = m square + n square and X + Y = 2 m

Answer 1

mx-ny=m^2+n^2+2mn-2mn

mx-ny=(m+n)^2-2mn________ eq. 1

x+y=2m________eq. 2

sub. eq. 2 in eq. 1

mx-ny=(m+n)^2-(x+y)n

mx-ny=(m+n)^2-nx-ny

add ny to both sides

mx-ny+ny=(m+n)^2-nx-ny+ny

mx=(m+n)^2-nx

mx+nx=(m+n)^2

Divide both sides by m+n

x=m+n

sub. x=m+n in eq. 1

(m+n)+y=2m

y=2m-m-n

y=m-n

Therefore, x=m+n, y=m-n