#1**+1 **

Solve the following system:

{7 x + 8 y = 14 | (equation 1)

-7 x - 7 y = -21 | (equation 2)

Add equation 1 to equation 2:

{7 x + 8 y = 14 | (equation 1)

0 x+y = -7 | (equation 2)

Subtract 8 × (equation 2) from equation 1:

{7 x+0 y = 70 | (equation 1)

0 x+y = -7 | (equation 2)

Divide equation 1 by 7:

{x+0 y = 10 | (equation 1)

0 x+y = -7 | (equation 2)

Collect results:

**Answer: | x = 10 and y = -7**

Guest May 17, 2017

#2**+1 **

Α=7x+8y=14

B=-7x-7y=-21

Α+Β=...y=14-21 y=-7 so

in A=7x+8(-7)=14<=>

<=>x=(14+56)/7<=>x=10

x=10 and y=-7

Whitespy001
May 17, 2017

edited by
Guest
May 17, 2017