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# C1 co-ordinate geometry...again :/ watch

1. I'm really stuck on this question, I don't know whether it's because it has an unknown or what..but I don't really know where to start.
The question is:

The straight line passing through point P(2,1) and the point Q(k,11) has gradient -.
a) Find the equation of the line in terms of x and y only.
b) Determine the value of k.

I have no idea where to start so a step by step explanation, or anything at all infact, would be very much appreciated. Thanks
2. You know it is in the form y = mx + b.

y - y1 = m(x - x1).

You know m as it is a straight line. (given points).

Sub in 11 to find k.
3. you have been given a point on a given line, as well as its gradient...which is what you need to construct an equation

try using y-(b) = m(x -a)
where a=2, b=1 and m=-5/12

simplify and this gives the equation

then use the co-ordinates for Q
ie. substitute in y=11 and then solve to find k

Hope that helps!

...someone got there before me
4. Thanks guys :]] God, I am truly hopless at maths! >.<

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