Question

Solve
the
following by substitution method
2x+3y=9 3x+4y=5​

Answer 1

Explanation:

Solution :

The given equation are

2x + 3y = 9 ....(i)

3x + 4y = 5 ....(ii)

From equation (ii), we get

4y = 5 – 3x

=> y = 5 – 3x/4

Substituating this value of y in equation (i), we get

2x + 3y = 9

=> 2x + 3(5 – 3x/4) = 9

=> 2x + (15 – 9x/4) = 9

=> 8x + 15 – 9x/4 = 9

=> 8x – 9x + 15 = 36

=> –x = 36 – 15

=> –x = 21

=> x = 21/–1

=> x = –21.

Substituating this value of x in equation (ii), we get

3x + 4y = 5

=> 3(–21) + 4y = 5

=> –63 + 4y = 5

=> 4y = 5 + 63

=> 4y = 68

=> y = 68/4

=> y = 17.

Hence :

The solution is x = –21 and y = 17.