# Point of Intersection

• Sep 4th 2010, 12:03 PM
watp
Point of Intersection
Hi there,

The formula's are:
$\displaystyle y = -\frac{4}{3}x + 12.33$
$\displaystyle y= \frac{3}{4}x + 4$

I'm unsure about how I go about it? I can do simultaneous equations and stuff, but we haven't really covered it.

Can anyone point me in the right direction? I'm think I need to move the $\displaystyle x$ to the other side, but I'm not sure.

• Sep 4th 2010, 12:06 PM
yeKciM
Quote:

Originally Posted by watp
Hi there,

The formula's are:
$\displaystyle y = -\frac{4}{3} + 12.33$
$\displaystyle y= \frac{3}{4} + 4$

I'm unsure about how I go about it? I can do simultaneous equations and stuff, but we haven't really covered it.

Can anyone point me in the right direction? I'm think I need to move the $\displaystyle x$ to the other side, but I'm not sure.

are you sure that you type that correctly here :D

(that's just two horizontal lines :D:D:D:D )
• Sep 4th 2010, 12:15 PM
watp
Quote:

Originally Posted by yeKciM
are you sure that you type that correctly here :D

(that's just two horizontal lines :D:D:D:D )

Ha, I missed the x out ;)
• Sep 4th 2010, 12:36 PM
yeKciM
Quote:

Originally Posted by watp
Hi there,

The formula's are:
$\displaystyle y = -\frac{4}{3}x + 12.33$
$\displaystyle y= \frac{3}{4}x + 4$

I'm unsure about how I go about it? I can do simultaneous equations and stuff, but we haven't really covered it.

Can anyone point me in the right direction? I'm think I need to move the $\displaystyle x$ to the other side, but I'm not sure.

$\displaystyle \displaystyle y=- \frac {4x}{3}+12.33$
$\displaystyle \displaystyle y= \frac {3x}{4}+4$

so let's say from second you express the x like :

$\displaystyle \displaystyle y= \frac {3x}{4}+4 \Rightarrow 4y=3x+16 \Rightarrow 3x=4y-16 \Rightarrow x= \frac {4y-16}{3}$

and put in first one ....

$\displaystyle \displaystyle y=- \frac {4x}{3}+12.33$

$\displaystyle \displaystyle y=- \frac {4(\frac {4y-16}{3} )}{3}+12.33$

$\displaystyle \displaystyle y=- \frac {\frac {16y-64}{3} }{3} +12.33$

so you solve for y.... and just get it back in to equation for x

$\displaystyle \displaystyle x = \frac {4y-16}{3}$

and you should get that for x=4 they intersect :D
• Sep 4th 2010, 12:40 PM
watp
Quote:

Originally Posted by yeKciM
$\displaystyle \displaystyle y=- \frac {4x}{3}+12.33$
$\displaystyle \displaystyle y= \frac {3x}{4}+4$

so let's say from second you express the x like :

$\displaystyle \displaystyle y= \frac {3x}{4}+4 \Rightarrow 4y=3x+16 \Rightarrow 3x=4y-16 \Rightarrow x= \frac {4y-16}{3}$

and put in first one ....

$\displaystyle \displaystyle y=- \frac {4x}{3}+12.33$

$\displaystyle \displaystyle y=- \frac {4(\frac {4y-16}{3} )}{3}+12.33$

$\displaystyle \displaystyle y=- \frac {\frac {16y-64}{3} }{3} +12.33$

so you solve for y.... and just get it back in to equation for x

$\displaystyle \displaystyle x = \frac {4y-16}{3}$

and you should get that for x=4 they intersect :D

Thanks yeKciM, I'll give it a try :)