If x = -y and y > 0, which of the following is wrong? (a) x2 y > 0 (

1.	If x = -y and y > 0, which of the following is wrong? (a) x2 y > 0 (b) x + y = 0 (c) xy ˂ 0 (d) 1/x - 1/y = 0
Answer» Correct answer = (d) 1/x - 1/y = 0 Given: x = -y and y > 0 Now, we have: (i) x² y On substituting x = -y, we get: (-y)² y = y³ > 0 (∵ y > 0) This is true. (ii) x + y On substituting x = -y, we get: (-y) + y = 0 This is also true. (iii) xy On substituting x = -y, we get: (-y)y = -y² (∵ y > 0) This is again true. (iv) 1/x - 1/y = 0 ⇒ y−x/xy = 0 On substituting x = -y, we get: y−(−y) (−y)y = 0 ⇒ 2y/−y²= 0 ⇒ 2y = 0 ⇒ y = 0.

If x = -y and y > 0, which of the following is wrong? (a) x2 y > 0 (b) x + y = 0 (c) xy ˂ 0 (d) 1/x - 1/y = 0

Answer»

Correct answer = (d) 1/x - 1/y = 0

Given:

x = -y and y > 0

Now, we have:

(i) x² y

On substituting x = -y, we get:

(-y)² y = y³ > 0 (∵ y > 0)

This is true.

(ii) x + y

On substituting x = -y, we get:

(-y) + y = 0

This is also true.

(iii) xy

On substituting x = -y, we get:

(-y)y = -y² (∵ y > 0)

This is again true.

(iv) 1/x - 1/y = 0

⇒ y−x/xy = 0

On substituting x = -y, we get:

y−(−y) (−y)y = 0 ⇒ 2y/−y²= 0 ⇒ 2y = 0 ⇒ y = 0.