Question 63542
QUESTION:

Solve the system by addition or substitution.
     3x – 4y = 8
     6x – 2y = 10


ANSWER:
.
     3x – 4y = 8  -------------------------(1)

     6x – 2y = 10 --------------------------(2)

Multiply first equation  2

==> 2 ( 3X - 4Y ) = 2 * 8

==> 2*3x - 2*4y  = 16

==> 6x - 8y = 16  ------------------------(3)


Subtract  equation (2) from equation (3)

==> 6x - 8y  -( 6x - 2y )= 16  -10

==> 6x - 8y  - 6x + 2y = 6  

==> 6x - 6x - 8y + 2y = 6

==>  -6y = 6

==>  y = 6 /-6

==> y = -1



Now  input the value  y = -1 in  first equation.

==> 3x – 4 *-1 = 8

==> 3x + 4 = 8

==> 3x = 8-4

==> 3x = 4

==>  x = 4/3



So the solution is,

x= 3/4 and y = -1


Hope you understood.


Regards.

praseenakos@yahoo.co.in