Question

5x+2y=15 and 9x+3y=12
find the value of x and y​

Answer 1

Answer:

equation 1 :- 5x+2y=15

equation 2 :- 9x+3y =12

now multiply equation 1 by 3 , and multiply equation 2 by 2 , and then subtrac two equation 2 from equation 1.

so we get , 15x+6y -18x- 6y = 45-24

so -3x= 21

so X= -7

put this value of X in equation 1

so we get , 2y = 15-(5*(-7))

so 2y = 15-(-35)

so 2y = 50

so y = 25

Answer 2

Answer:

x = -7 , y = 25

Solution:

The given equations are :

5x + 2y = 15 ------(1)

9x + 3y = 12 -------(2)

Eq-(2) can be rewritten as ;

=> 9x + 3y = 12

=> 3(3x + y) = 12

=> 3x + y = 12/3

=> 3x + y = 4

=> y = 4 - 3x --------(3)

Now,

Putting y = 4 - 3x in eq-(1) , we get ;

=> 5x + 2y = 15

=> 5x + 2(4 - 3x) = 15

=> 5x + 8 - 6x = 15

=> 5x - 6x = 15 - 8

=> -x = 7

=> x = -7

Now,

Putting x = -7 in eq-(3) , we have ;

=> y = 4 - 3x

=> y = 4 - 3•(-7)

=> y = 4 + 21

=> y = 25

Hence,

x = -7

y = 25