Question 12 - Figure it out - Page 102 to 105 - Chapter 4 Class 7 - Expressions using Letter-Numbers (Ganita Prakash)

Transcript

Question 12 Look at the matchstick pattern below. Observe and identify the pattern. How many matchsticks are required to make 10 such squares. How many are required to make w squares?From image we note that To make 1 square, you need 4 matchsticks. To make 2 squares, you add 3 more matchsticks, for a total of 7. To make 3 squares, you add another 3 matchsticks, for a total of 10. We observe that the pattern is that you start with 1 matchstick and add 3 matchsticks for every square you want to make. The formula is: Number of matchsticks = 3w + 1, where 'w' is the number of square So, our expression is formed. Now, we need to find Number of matchsticks required to make 10 squares Number of matchstick required to make 10 squares Since we have to make 10 squares ∴ w = 10 Putting w = 10 in formula Number of matchsticks = 3w + 1 = 3 × 10 + 1 = 30 + 1 = 31