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Mathematics

The point of intersection of the lines x + y = 8 and x - y = 0 lies on the line mx - 2y = 0; the value of m is :

  1. 3

  2. 4

  3. 2

  4. -2

Straight Line Eq

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Answer

Given,

1st Equation :

⇒ x + y = 8

⇒ x = 8 - y ……(1)

2nd equation :

⇒ x - y = 0

⇒ x = y ………(2)

Substituting value of x from equation (2) in (1), we get :

⇒ y = 8 - y

⇒ y + y = 8

⇒ 2y = 8

⇒ y = 82\dfrac{8}{2} = 4.

From equation (2), we get :

⇒ x = y = 4.

Point of intersection of lines x + y = 8 and x - y = 0 is (4, 4).

Given, point of intersection lies on the line mx - 2y = 0.

Substituting values we get :

⇒ 4m - 2 × 4 = 0

⇒ 4m - 8 = 0

⇒ 4m = 8

⇒ m = 84\dfrac{8}{4} = 2.

Hence, Option 3 is the correct option.

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