Solve the following equations by trial and error method. (i) 2 + y =

1.	Solve the following equations by trial and error method. (i) 2 + y = 7 (ii) a – 2 = 6 (iii) 5m = 15 (iv) 2n = 14
Answer» (i) 2 + y = 7 if y = 1; LHS = 2 + y = 2 + 1 = 3 ≠ 7 If y = 2; LHS = 2 + 2 = 4 ≠ 7 If y = 3; LHS = 2 + 3 = 5 ≠ 7 If y = 4; LHS = 2 + 4= 6 ≠ 7 If y = 5; LHS = 2 + 5 = 7 = 7 = RHS ∴ y = 5 is the solution of 2 + y = 7 (ii) a – 2 = 6 As a – 2 = 6 ; the value of ‘a’ must be greater than 6. If a = 7; LHS = 7 – 2 = 5 ≠ 6 If a = 8; LHS = 8 – 2 = 6 = RHS ∴ a = 8 is the solution of a – 2 = 6 (iii) 5m = 15 If m = 1 then LHS = 5 × 1 = 5 ≠ b15 m = 2 then LHS = 5 × 2 = 10 ≠ 15 m = 3 then LHS = 5 × 3 = 15 = 15 ∴ m = 3 is the solution of 5m = 15 (iv) 2n = 14 If n = 1 then LHS = 2 × 1 = 2 ≠ 14 n = 2 then LHS = 2 × 2 = 4 ≠ 14 n = 3 then LHS = 2 × 3 = 6 ≠ 14 n = 4 then LHS = 2 × 4 = 8 ≠ 14 n = 5 then LHS = 2 × 5 = 10 ≠ 14 n = 6 then LHS = 2 × 6 = 12 ≠ 14 n = 7 then LHS = 2 × 7 = 14 ≠ 14

Solve the following equations by trial and error method. (i) 2 + y = 7 (ii) a – 2 = 6 (iii) 5m = 15 (iv) 2n = 14

Answer»

(i) 2 + y = 7

if y = 1; LHS = 2 + y = 2 + 1 = 3 ≠ 7

If y = 2; LHS = 2 + 2 = 4 ≠ 7

If y = 3; LHS = 2 + 3 = 5 ≠ 7

If y = 4; LHS = 2 + 4= 6 ≠ 7

If y = 5; LHS = 2 + 5 = 7 = 7 = RHS

∴ y = 5 is the solution of 2 + y = 7

(ii) a – 2 = 6

As a – 2 = 6 ; the value of ‘a’ must be greater than 6.

If a = 7; LHS = 7 – 2 = 5 ≠ 6

If a = 8; LHS = 8 – 2 = 6 = RHS

∴ a = 8 is the solution of a – 2 = 6

(iii) 5m = 15

If m = 1 then LHS = 5 × 1 = 5 ≠ b15

m = 2 then LHS = 5 × 2 = 10 ≠ 15

m = 3 then LHS = 5 × 3 = 15 = 15

∴ m = 3 is the solution of 5m = 15

(iv) 2n = 14

If n = 1 then LHS = 2 × 1 = 2 ≠ 14

n = 2 then LHS = 2 × 2 = 4 ≠ 14

n = 3 then LHS = 2 × 3 = 6 ≠ 14

n = 4 then LHS = 2 × 4 = 8 ≠ 14

n = 5 then LHS = 2 × 5 = 10 ≠ 14

n = 6 then LHS = 2 × 6 = 12 ≠ 14

n = 7 then LHS = 2 × 7 = 14 ≠ 14