Point of Intersection

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troublemaker676

Junior Member
Joined
Sep 1, 2005
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Here's the problem i have no idea to solve,

Find the point of intersection of these two lines:

y=(-1/3)x + (17/2)
y=(-9/11)x + (17/2)

I just need someone to show me the process of how it is done and then i will be able to do the others that i have to do.
 
The point of intersection is where the lines cross, where the x's and y's are equal. So set the equations equal, solve for x, and then back-solve for y.

. . . . .(-1/3)x + (17/2) = (-9/11)x + (17/2)

Solve.

Eliz.
 
Point of intersection

So when i solve for x i get zero, then i put it back in for x in the original equation, y= (-1/3)x + (17/2)
y= (-1/3)0 + (17/2)

so y= 17/2, that means the point is (0,17/2), is this correct? And does it matter which equation you put 0 back in for x?
 
Since the point of the intersection is that the x- and y-coordinates are equal, no, it doesn't matter which of the lines you plug into.

Eliz.
 
For a problem like: 4x-2y=6 and -3x+7y=67, and you must find the point of intersection would you just put both equations into y=mx=b form, or is there an easier way to do it?
 
The "easier way" will depend upon the specifics of the particular system. In this particular system, it might be simplest to solve the first equation for "y=", since the 2 will divide evenly into the 4 and the 6. But that's just a matter of taste. Somebody else might prefer to multiply the first equation by 3 and the second equation by 4, and then solving by addition. There's no one right way for these things; only right answers.

Eliz.
 
Alright i have another question on point of intersection and hopefully the last, the problem is 19x-67y=-3401, and 301x+73y=-10771, now when i solved for x i got this huge fraction(4743927630/91852980), and had to put it into decimal form which is 51.6, then i put x back in for the original equation and got another weird fraction that i put into decimal form which was -360.3. So for the point i got (51.6,-360.3). This just dosn't seem right to me. I think i am way off. Can someone tell me if this answer is right, and if it si where i went wrong?
 
Please post new questions as new threads, not as replies to old questions. Thank you.

To check your answer to any "solving" problem, plug your solution into the original question, and see if it works. In your case:

. . . . .19(51.6) - 67(-360.3) = ?

If you get "-3401", then plug x and y into the other equation. If you get the right answer there, too, you're done. If not, then check your work.

There is nothing (other than perhaps habit) that says your answers have to be whole numbers or small-numbered fractions.

Eliz.
 
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