Example 2 - Chapter 2 Class 9 - Introduction to Linear Polynomials (Ganita Manjari

Transcript

Example 2 A rectangular garden of length l metres and width w metres has to be fenced and decorated. A wire fence is to be laid along the length costing ₹100 per metre and a wooden fence is to be built along the width costing ₹80 per metre. Special seeds have to be sown throughout the garden which will cost ₹50 per square metre. What will be the total cost incurred? Now, Total cost = Cost of fencing the Garden Length + Cost of fencing the Garden Width + Cost of sowing seeds in the Garden Let’s find each one by one Cost of fencing Garden Length Cost is ₹ 100 per meter, And length of garden is l + l (Both sides of the garden) So, Cost of fencing Garden Length = ₹ 100 × (l + l) = 100 × 2l = ₹ 200l Cost of fencing Garden Width Cost is ₹ 80 per meter, And width of garden is w + w (Both sides of the garden) So, Cost of fencing Garden Width = ₹ 80 × (w + w) = 80 × 2w = ₹ 160w Cost of sowing seeds in the Garden Given that special seeds have to be sown throughout the garden which will cost ₹50 per square metre Since seeds will be sown along the area of the garden Cost of sowing seeds in the Garden = Area of garden × Cost per squre meter = (Length × Width) × 50 = l × w × 50 = ₹ 50lw Thus, Total cost = Cost of fencing the Garden Length + Cost of fencing the Garden Width + Cost of sowing seeds in the Garden = 200l + 160w + 50lw Here, Terms are 200l, 160w and 50lw Variables are l & w 200, 160 and 50 are coefficients of l, w & lw respectively Constant – there is no constant