Question

find the value of k. 2x + 5 y = 9 and 4x + (k+1)y = 18

Answer 1

Answer:

[2x +5y = 9] ×4

[4x+ (k+1)y = 18] ×2

8x +20y =36

8x +2(k+1)y =36

– – –

20y-2(k+1)y =0

2y[10-(k+1)] =0

-(k+1) = -10

k+1 =10

k = 9

Answer 2

Answer:

2x+5y=9......1st eq and 4x+(k+1)y=18......2eq subtract 1st eq from 2nd eq then we get 2x+(k+1)y-5y=9....3rd eq from 1st eq we get 2x=9-5y.... 4th eq substitute 4th eq in 3rd eq we get the final answer that is k=9