Question

solve the equation 2x+3y=9 and 3x+4y=5 by substitutions method​

Answer 1

Answer:

We have,

2x+3y=9 ……. (1)

3x+4y=5 …… (2)

Now,

y=

3

9−2x

On putting the value of y, in equation (2), we get

3x+4(

3

9−2x

)=5

3x+

3

36−8x

=5

9x+36−8x=15

x=15−36

Now, put the value of x in equation (1), we get

y=

3

9−2(−21)

y=

3

9+42

y=

3

51

=17

Hence, this is the answer.

Answer 2

Step-by-step 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.