What will be the value of xy, if $$x^{2}+y^{2}=45$$ and $$x-y=5$$ ?
Given : $$x^{2}+y^{2}=45$$ ----------(i)
Also, $$x-y=5$$
Squaring both sides, we get :
=>Â $$(x-y)^2=(5)^2$$
=> $$x^2+y^2-2xy=25$$
Substituting value from equation (i),
=> $$45-2xy=25$$
=> $$2xy=45-25=20$$
=> $$xy=\frac{20}{2}=10$$
=> Ans - (A)
Create a FREE account and get:
