ICSE Class 9 Answered

Given simultaneous linear equations are

7x - 10y = 4 ....................... (1)

12x+18y = 1 .......................(2)

Above eqn.(2) is simplified as

2x +3y = 1/6 ..................(3)

2x = (1/6) - 3y

x = (1/12) - (3/2)y

By substituting x from above expression , we can eliminate x and rewrite eqn.(1) as

(7/12) - (21/2)y - 10 y = 4

-(41/2)y = 4 - (7/12) = (41/12)

y = -1/6

By substituting y = -1/6 in eqn.(3) , we get, x = 1/3

4x+6y = (4/3)-(6/6) = 1/3

8y-x = -(8/6) -(1/3) = -5/3