SOLUTION: systems by elimination 6x-7y=21 3x+7y=6 answer:(3, -3/7) need a full break down of how my book got this answer i understand how they got the 3 but dont understand ho

Question 186410: systems by elimination
6x-7y=21
3x+7y=6

answer:(3, -3/7)

need a full break down of how my book got this answer i understand how they got the 3 but dont understand how they got -3/7
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
If you understand how they got the '3' in the ordered pair

, then this simply means that they found that

Now pick any equation (I'm going to pick the first one, it doesn't matter which one you choose).

Start with the first equation

Plug in the previously found solution

Multiply

Subtract 18 from both sides.

Combine like terms.

Divide both sides by -7 to isolate 'y'

Reduce.

So the other solution is which means that the ordered pair solution is

RELATED QUESTIONS
6x-7y=21 and 3x+7y=6 answer:(3, -3/7) need to know how my book got the -3/7... (answered by stanbon)

18x^2 +9x + 1=0 answer: x= -1/3 or -1/6 need a full break down of how my text (answered by jim_thompson5910)

18x^2 + 9x +1=0 answer:x= -1/3 or -1/6 need a full break down of how my book (answered by ankor@dixie-net.com)

x^2 + 2x= 3/4=0 answer x= -3/2 or -1/2 need a full break down of how my book... (answered by Alan3354)

solve 2r^2 + 3r-1=0 answer: -3 + sqrt 17/4, -3-sqrt 17/4 need a full break down... (answered by yuendatlo)

x^4 - x^3 - 9x^2 +14x - 4/ x^2 -3x + 1 answer:x^2 + 2x - 4 need a full break... (answered by Mathtut)

2x-3y= 7 3x+7y= -1 answer (2,-1) need a break down of how my text book got the (answered by jim_thompson5910)

14y^2 - 17y - 9 /2y +3 answer:7y - 19 + 48/2y + 3 need break down of how my book... (answered by Mathtut)

1=3x^2+ 2x answer x= -1 or 1/3 need a break down of how my text book got this... (answered by Mathtut)