Page 169 - Maths Class 06

From the above table, we find that LHS = RHS, when x = 4.
\ Solution is x = 4.
EX AM PLE 2. Solve the equa tion 2x - 7 = 8 - x by the trial and er ror method

SOLUTION : We try sev eral val ues of x and find the val ues of the LHS and the RHS. We stop when for a
par tic u lar value of x, LHS =RHS.

x LHS RHS
1 2 1 7´ - = – 5 8 1 7- =

2 2 2 7´ - = - 3 8 2- = 6

3 2 3 7´ - = - 1 8 3- = 5
4 2 4 7´ - = 1 8 4- = 4

5 2 5 7´ - = 3 8 5- = 3

\ x = 5 is the solution of the given equation.
1
EX AM PLE 3. Solve the equa tion y + 5 = 8 by the trial and er ror method.
3

SOLUTION : We make a guess and try sev eral val ues of y and find the val ues of the LHS as well as the
RHS in each case. We stop when for a par tic u lar value of y. LHS = RHS.
y LHS RHS

3 1 8
´ 3 + 5 = 6
3

6 1 ´ 6 + 5 = 7 8
3

9 1 ´ 9 + 5 = 8 8
3

Thus, when y = 9, we have LHS = RHS
\ y = 9 is the solution of the given equation.

Exercise11.4

1. Write each of the following statements as an equation:
(a) 5 times a number equals 40.

(b) 3 less than 4 times a number is 17.
(c) 25 exceeds a number by 1.
(d) A number increased by 8 equals 15.
(e) 5 subtracted from thrice a number is 16.

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