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**the stuck guy****Guest**

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|?

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,552

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

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 15,142

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

Character is who you are when no one is looking.

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,552

Probably the British tradition?

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

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 15,142

Yes, very much British

Character is who you are when no one is looking.

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