# graphing linear equation, need help.

• Nov 10th 2010, 03:14 PM
jingming90
graphing linear equation, need help.
-x+4y=9

what's the best number to put for X

any suggestion?
• Nov 10th 2010, 03:17 PM
skeeter
Quote:

Originally Posted by jingming90
-x+4y=9

what's the best number to put for X

any suggestion?

x = 0 ... you get the y-intercept

y = 0 ... you get the x-intercept
• Nov 10th 2010, 03:21 PM
jingming90
y do i have to find the x and y intercept first? does it make it easier?
• Nov 10th 2010, 03:27 PM
skeeter
Quote:

Originally Posted by jingming90
y do i have to find the x and y intercept first? does it make it easier?

you asked for a suggestion ... I gave you one.

you'll have to determine if it makes graphing the line "easier" than some other method you know.
• Nov 10th 2010, 03:46 PM
pickslides
Quote:

Originally Posted by jingming90
y do i have to find the x and y intercept first? does it make it easier?

I think so, you have a point on the x-axis and a point on the y-axis, just join the 2 and you have a line.

As both calcs have a zero, the calclations are simple.
• Nov 10th 2010, 04:25 PM
jingming90
what should i do if the equation look somthing like -2x=4y
??
• Nov 10th 2010, 04:55 PM
mr fantastic
Quote:

Originally Posted by jingming90
what should i do if the equation look somthing like -2x=4y
??

If the line passes through (0, 0) then you need to get another point. Common sense would suggest that you should substitute a simple value of x to get that point eg. x = 1 => y = -1/2 so that (1, -1/2) is a point.