Quadratic Equations | Exercise 4.3

Question 3

Is it possible to design a rectangular mango grove whose length is twice its breadth, and the area is 800 m2800\text{ m}^2? If so, find its length and breadth.

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Solution

We need to check if a rectangular mango grove with specific dimensions and area is possible.

Step 1 — Define dimensions and area

Let's assume the breadth of the mango grove. Let the breadth be xx meters. The problem states the length is twice its breadth. So, the length will be 2x2x meters. The area of a rectangle is length multiplied by breadth. We can write the area as x×2xx \times 2x. This simplifies to 2x22x^2. The problem gives the area as 800 m2800 \text{ m}^2. We can now set up an equation.

2x2=8002x^2 = 800

Diagram 1

Step 2 — Solve for the breadth

We need to solve our equation for xx. First, let's divide both sides by 2.

x2=8002x^2 = \frac{800}{2}

x2=400x^2 = 400

Now, we take the square root of both sides.

x=±400x = \pm\sqrt{400}

x=±20x = \pm 20

The breadth of a grove cannot be negative. So, we choose the positive value for xx.

Breadth=20 m\boxed{\text{Breadth} = 20 \text{ m}}

Step 3 — Calculate the length

We know the breadth is 20 meters. The length is twice the breadth. So, we multiply the breadth by 2.

Length=2×20\text{Length} = 2 \times 20

Length=40 m\boxed{\text{Length} = 40 \text{ m}}

Since we found positive values for both length and breadth, it is possible.

Answer

(i) Yes, it is possible to design such a mango grove. (ii) The length of the mango grove is 40 m. (iii) The breadth of the mango grove is 20 m.

More questions in Exercise 4.3

Q1

Find the nature of the roots of the following quadratic equations. If the real roots exist, find them:

(i) 2x23x+5=02x^2 - 3x + 5 = 0

(ii) 3x243x+4=03x^2 - 4\sqrt{3} x + 4 = 0

(iii) 2x26x+3=02x^2 - 6x + 3 = 0

Q2

Find the values of kk for each of the following quadratic equations, so that they have two equal roots.

(i) 2x2+kx+3=02x^2 + kx + 3 = 0

(ii) kx(x2)+6=0kx (x - 2) + 6 = 0

Q3

Is it possible to design a rectangular mango grove whose length is twice its breadth, and the area is 800 m2800\text{ m}^2? If so, find its length and breadth.

Q4

Is the following situation possible? If so, determine their present ages.

The sum of the ages of two friends is 2020 years. Four years ago, the product of their ages in years was 4848.

Q5

Is it possible to design a rectangular park of perimeter 80 m80\text{ m} and area 400 m2400\text{ m}^2? If so, find its length and breadth.

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