Example 1 - Chapter 4 Class 7 - Expressions using Letter-Numbers (Ganita Prakash)

Transcript

Example 1 Shabnam is 3 years older than Aftab. When Aftab’s age 10 years, Shabnam’s age will be 13 years. Now Aftab’s age is 18 years, what will Shabnam’s age be?Given that Shabnam is 3 years older than Aftab So, Shabnam’s age = Aftab’s age + 3 Now, given that When Aftab’s age 10 years, Shabnam’s age will be 13 years. Now Aftab’s age is 18 years, what will Shabnam’s age be? Putting Aftab’s age = 18 years Shabnam’s age = Aftab’s age + 3 Shabnam’s age = 18 + 3 Shabnam’s age = 21 But we had to write down so much text – Aftab’’s age, Shabnam’s age We could simplify it by writing Aftab’’s age = a Shabnam’s age = s Thus, we can write Shabnam’s age = Aftab’s age + 3 As s = a + 3 This is much more cleaner, and easier to read – and easier to solve. Like, we can put different values of a, to get different values of s Here, a & s are called variables or letter-numbers a + 3 is an algebraic expression (without equal sign) s = a + 3 is an equation with variables