SSC CHSL 20 Dec 2015 Shift 2 Paper

Question : 139 of 200

Marks: +1, -0

The length of a room is 3 m more than its breadth. If the area of the floor of the room is 70 m, then the perimeter of the floor will be

Solution:

Let breadth =

x

m
⇒ Let breadth =

(x+3)

m
⇒ Area =

x(x+3)=70

⇒

x^2 + 3x − 70 = 0

⇒

x^2 + 10x − 7x − 70 = 0

⇒

x(x + 10) − 7(x + 10) = 0

⇒

(x − 7)(x + 10) = 0

⇒

x = 7, −10

∵ Breadth cannot be neagative , ⇒ x ≠ −10
∴ Perimeter =

2(l + b)

2(x + x + 3) = 4x + 6

4(7) + 6 = 28 + 6 = 34

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