Question
Hi, I need help on this problem:Solve the system of equation by giving an ordered pair for 14x +3y = 115
7x +3y = 80
Use the 3 Methods in your work.
Thank You, I am not sure how to use graphing, substitution, and elimination, please show these methods.
7x +3y = 80
Use the 3 Methods in your work.
Thank You, I am not sure how to use graphing, substitution, and elimination, please show these methods.
Answers
elimination:
subtract the 2nd from the first (you have 3y in both)
7x = 35
x = 5
sub into the 2nd:
7(5) + 3y = 80
3y = 45
y = 15
They intersect at (5,15)
substitution: from the 2nd :
3y = 80-7x
plug into the first,
14x + 80-7x = 115
7x = 35
x = 5
then 3y = 80-7x = 80 - 35
3y = 45
y = 15 , same as above
graphing
http://www.wolframalpha.com/input/?i=plot+14x+%2B3y+%3D+115+%2C+7x+%2B3y+%3D+80
I assume you know how to graph a straight line
subtract the 2nd from the first (you have 3y in both)
7x = 35
x = 5
sub into the 2nd:
7(5) + 3y = 80
3y = 45
y = 15
They intersect at (5,15)
substitution: from the 2nd :
3y = 80-7x
plug into the first,
14x + 80-7x = 115
7x = 35
x = 5
then 3y = 80-7x = 80 - 35
3y = 45
y = 15 , same as above
graphing
http://www.wolframalpha.com/input/?i=plot+14x+%2B3y+%3D+115+%2C+7x+%2B3y+%3D+80
I assume you know how to graph a straight line