Question

Solve the following equations.

3a + 5b = 12

7a + 9b = 16.​

Answer 1

Answer:

Given ,

3a + 5b = 12 -------------- Equation 1

7a + 9b = 16 -------------- Equation 2

To Balance Equation We Have To Multiply Equation 1 By 7 & Equation 2 By 3

7 × ( 3a + 5b = 12 )

3 × ( 7a + 9b = 16 )

21a + 35b = 84 ------------- Equation 3

21a + 27b = 48 ------------- Equation 4

From Equation 3 & 4

21a + 35b = 84

21a + 27b = 48

- - - ( Changing Signs )

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8b = 36

b = 9/2

3a + 5b = 12

Put b = 9/2 ,

3a + 5 × 9 / 2 = 12

3a = 12 - 45 / 2

3a = 24 - 45 / 2

3a = -21 / 2

a = -21 / 6

a = -7 / 2

_______________

| a = -7 / 2 , b = 9/2 |

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