SSC CHSL 4 Mar 2018 Shift 3 Paper

Section: English Language

Question : 4 of 100

Marks: +1, -0

What will be the value of xy, if

x^2+y^2=45

and

x-y=5

Solution:

Given :

x^2+y^2=45

----------(i)
Also,

x − y = 5

Squaring both sides, we get :
⇒

(x − y) ^2 = (5) ^2

⇒

x^ 2 + y^ 2 − 2xy = 25

Substituting value from equation (i),
⇒

45 − 2xy = 25

⇒

2xy = 45 − 25 = 20

⇒

xy= 20/2 = 10

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