How do solve the following linear system?: y=2x+1,8x+3y=9?

1 Answer
Jan 7, 2016

x = - 6 , y = 13

Explanation:

write the equations with labels on them- this helps when wedo operations on them.

y + 2x = 1 (1)
3y + 8x = - 9 (2)

to eliminate y multiply (1) by - 3

(- 3y) - 6x = - 3 (3)

now add (2) and (3 ) and y is eliminated.

2x = - 12 x=6

now substitute x = - 6 in (1) ( you could substitute in (2) if you wish )

y + 2×(6)=1y12=1y==1+12=13

check: x= - 6 , y = 13 in (1)→ 13 + 2 (- 6) =13 - 12 =1 and equation is true.

check x = - 6 , y = 13 in (2) →3(13) + 8(- 6 ) = 39 - 48 = - 9 and equation is also true.