Evaluating an expression with one variable

Substituting 2 in place of m, we get Value of an expression To find the value of an algebraic expression, we need to substitute the value of the variable in the algebraic expression For example: Value of m + 8 for m = 2 will be m+8 Substituting 2 in place of m, we get (2) + 8 = 10

Substituting the value 7 for b, we get Example 1: Find a value for the expression 3b when b =7 3b Substituting the value 7 for b, we get 3b = 3 x (7) = 21 Take out b and replace it with 7 Put 7 inside a bracket 21 is the value of the expression Ans: 21

Substituting the value 8 for x, we get Example 2: Find a value for the expression x - 20 when x =8 x-20 Substituting the value 8 for x, we get x-20 = (8) - 20 = -12 -12 is the value of the expression Take out x and replace it with 8 Put 8 inside a bracket Ans: -12

Try these Find the value for the expression. a) x + 8 when x = 3 b) 12y when y = 2