Solve the system using substitution.
y = x -7
2x + y = 8
A. (-3,2)
B. (17,21)
C. (-2,-3)
D. (1,9)
E. (5,-2)
easy math?
2008-03-25 4:12 am
回答 (9)
2008-03-25 4:15 am
✔ 最佳答案
2x+1x-7=83x-7=8
Add 7 to both sides
3x-7+7=8+7
Substitute
3x=15
Solve for x
x=5
y=5-7
y=-2
ANSWER (5,-2) E
Hope that helps!
2008-03-25 11:21 am
e
2008-03-25 11:21 am
The answer is E, and yes, this is easy math. Very easy. Thanks for the challange-have a good night!
2008-03-25 11:20 am
Yep. Just as I predicted. Posting tons of nearly-identical questions, instead of learning the method from one answer so that you can do the rest. So here's an identical answer for you.
This page shows you all the different ways of solving sets of linear equations. Not that you'll actually read it:
http://mathforum.org/library/drmath/view/61608.html
And usual, you probably won't give out a "best answer" to anybody, since glancing at your past questions it seems that you never do.
This page shows you all the different ways of solving sets of linear equations. Not that you'll actually read it:
http://mathforum.org/library/drmath/view/61608.html
And usual, you probably won't give out a "best answer" to anybody, since glancing at your past questions it seems that you never do.
2008-03-25 11:19 am
2x+(x-7)=8
2x+x-7=8
3x-7=8
3x=8+7
3x=15
x=5
use the "x=5" substitute any of the two equations to find y.
y=5-7
y=-2
the answer is E.(5,-2)
2()
2x+x-7=8
3x-7=8
3x=8+7
3x=15
x=5
use the "x=5" substitute any of the two equations to find y.
y=5-7
y=-2
the answer is E.(5,-2)
2()
2008-03-25 11:17 am
y is the exact same thing as x - 7. In the second equation, wherever there is a y, throw it out and put in x - 7.
2x + (x - 7) = 8
2x + x - 7 = 8
3x - 7 = 8
3x = 15
x = 5
Now, in either equation, where there is an x you can throw it out and put in 5.
y = 5 - 7
y = -2
CHECK YOUR ANSWER.
2(5) + (-2) = 8
10 - 2 = 8
8 = 8 woohoo
(5, -2)
2x + (x - 7) = 8
2x + x - 7 = 8
3x - 7 = 8
3x = 15
x = 5
Now, in either equation, where there is an x you can throw it out and put in 5.
y = 5 - 7
y = -2
CHECK YOUR ANSWER.
2(5) + (-2) = 8
10 - 2 = 8
8 = 8 woohoo
(5, -2)
2008-03-25 11:16 am
E
2008-03-25 11:15 am
yup it's easy.
so do it :P
so do it :P
2008-03-25 11:15 am
use your brain what is your brain for playing or thinking?
收錄日期: 2021-05-03 13:57:22
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080324201217AAwlPJg