Question 3 - Figure it out - Page 102 to 105 - Chapter 4 Class 7 - Expressions using Letter-Numbers (Ganita Prakash)

Transcript

Question 3 (a) A snail is trying to climb along the wall of a deep well. During the day it climbs up ‘u’ cm and during the night it slowly slips down ‘d’ cm. This happens for 10 days and 10 nights (a) Write an expression describing how far away the snail is from its starting positionIn one day and one night, the snail's net movement is climbing up 'u' cm and slipping down 'd' cm. So, the net progress per day-night cycle is (u−d) cm. Since this happens for 10 days and 10 nights, the total distance from the start is 10 times the daily net progress. Expression: 10(u − d) or 10u−10d. Question 3 (b) A snail is trying to climb along the wall of a deep well. During the day it climbs up ‘u’ cm and during the night it slowly slips down ‘d’ cm. This happens for 10 days and 10 nights. (b) What can we say about the snail’s movement if d > u?If d > u then the value of (u−d) will be negative This means that each day, the snail will end up lower than where it started. ∴ The snail is making negative progress and is moving down the well instead of up.