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#1 2005-10-07 06:00:06

the stuck guy
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help plz

i have a question infront of be that reads" write down the gradient and y-intercept for each of these straight lines" then it says "b)      2y = 4x - 12 " i know how to set up the table but why is there a 2y what do i do when i am trying to find the co-ordinates like x|0|1|2|3|4|5|
                                                                                                   y|?

#2 2005-10-07 08:09:56

MathsIsFun
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Re: help plz

Straight lines are usually written in the form:

y = mx + b

(see Equation of a Straight Line)

So, you can change your equation to suit:

Start with: 2y = 4x - 12
Divide by 2: y = 2x - 6

Then for any x you can calculate y, for example: if x=4, then y = 2 4 - 6 = 8-6 = 2

And you can see that the gradient is 2 (because y changes by 2 when x changes by 1)

And the y intercept is when x=0, so: y=2x-6= 2 0 - 6 = -6


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

#3 2005-10-07 14:13:35

ganesh
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Re: help plz

In India,
y = mx + c
where c is the y intercept and -x/y is the slope (or gradient),
when written as y - mx - c = 0 smile


Character is who you are when no one is looking.

#4 2005-10-07 16:01:08

MathsIsFun
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Re: help plz

Probably the British tradition?


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

#5 2005-10-07 18:39:22

ganesh
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Re: help plz

Yes, very much British smile


Character is who you are when no one is looking.

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