Question 110139This question is from textbook Beginning Algebra
: Could you please tell me if I did some of this problem correct? It says to find the values for m and b the solution to the system is (-3,4).
5x+7y=b
mx+y=22
so I did this 5(-3)+7(4)=b b=5(-3)+7(4), b=-15+28, b=13, but I don't know what to do with mx+b=22???
Thanks you for your help!!
This question is from textbook Beginning Algebra
Found 2 solutions by stanbon, ankor@dixie-net.com:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! find the values for m and b the solution to the system is (-3,4).
5x+7y=b
mx+y=22
so I did this
5(-3)+7(4)=b
b=5(-3)+7(4),
b=-15+28,
b=13
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Now put the point values into the 2nd equation:
m*-3+4 = 22
m = 34
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Cheers,
Stan H.
Answer by ankor@dixie-net.com(22740)  (Show Source):
You can put this solution on YOUR website! It looks like you got half of it right:
This same problem came up a few weeks ago, this is what I submitted then
Perhaps it will help you.
Find values for m and b in the following system so that the solution to the system is (-3,4)
They want you find both equations of a two-equation system
Find the 1st equation:
5x + 7y = b
:
Find b by using x,y coordinates given -3, 4
5(-3) + 7(4) = b
-15 + 28 = b
b = + 13
:
Find the slope (m): using y = mx + 13, using the given coordinates again
y = mx + b
4 = m(-3) + 13
4 = -3m + 13
3m = 13 - 4
3m = 9
m = +3
:
the 1st equation: y = 3x + 13; (m = +3 and b = +13)
:
:
Find the 2nd equation:
mx + y = 22
Find the slope (m) using the given coordinates x,y; -3,4
m(-3) + 4 = 22
-3m = 22 - 4
-3m = 18
m = 18/-3
m = -6
:
Find b in the 2nd equation, using the given coordinates for x & y again
y = mx + b
4 = -6(-3) + b
4 = 18 + b
4 -18 = b
b = -14
:
The 2nd equation: y = -6x - 14; (m =- 6 and b = -14)
:
If you graphed these two equations, you would find that they intersect at the given coordinates of -3,4
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