KCET2013MathematicsTrigonometric Ratios & Identities
If x- y= 1 2 and x- y=1 , then (x+y) is equal to
Options
- A3 8
- B- 3 8
- C4 3
- D- 4 3
Correct answer
C. 4 3
Step-by-step solution
Given, x- y= 1 2 ...(i) and x- y=1...(ii) 2 x+y 2 x-y 2 = 1 2 ...(iii) and -2 x+y 2 x-y 2 =1...(iv) On dividing Eq. (iv) by Eq. (iii), we get gathered - ( x+y 2 )=2 ( x+y 2 )=-2 (v) Now, (x+y)= 2 ( x+y 2 ) 1- ² ( x+y 2 ) gathered ( 2 = 2 1- ² )= 2(-2) 1-(-2)² [using Eq. (v)] = -4 1-4 = -4 -3 = 4 3