NCERT Solution Class X Mathematics Quadratic Equations Question 3 (Ex 4.4)

Question 3:

Is it possible to design a rectangular mango grove whose length is twice its breadth, and the area is 800 m2?

If so, find its length and breadth.

Answer:

Let the breadth of mango grove be l.

Length of mango grove will be 2l.

Area of mango grove = (2l) (l) = = 2l2

2l= 800

l2 = 800/2 = 400

l2 − 400 = 0

Comparing this equation with al2 + bl + c = 0, we obtain a = 1 b = 0, c = 400

Discriminant = b2 − 4ac = (0)2 − 4 × (1) × (− 400) = 1600

Here, b2 − 4ac > 0

Therefore, the equation will have real roots. And hence, the desired rectangular mango grove can be designed.

l = ±20

However, length cannot be negative.

Therefore, breadth of mango grove = 20 m

Length of mango grove = 2 × 20 = 40 m

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