Question

solve by the elimination method a+9b=11, a+3b=-1

Answer 1

Elimination method

a+9b = 11 ---------> (1)

a+3b = 1 ------------> (2)

To eliminate the a value subtract the equation (2) from (1).

a+9b = 11

a+3b = 1

(-) (-)   (-)

_________

6b = 10

Divide to each side by 6.

6b/6 = 10/6

⇒ b = 5/3

Substitute the b value in (1).

a+9*5/3 = 11

a+15 = 11

Subtract 15 to each side.

a+15-15 = 11-15

⇒ a = -4

Solution a = -4,b = 5/3.

Answer 2

Elimination method

The system of equations are a + 9b = 11 ----> (1)

a + 3b = - 1 ----> (2)

To elminate the a variable subtract the equation (2) from (1).

     a + 3b = - 1

     a + 9b = 11

(-)   (-)        (-)

____________________

     - 6b = - 12

b = 2

Substitute the b value in equation (1).

a + 9(2) = 11

a + 18 = 11

a = 11 - 18

a = - 7

Solution a = -7 and b = 2.