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Straight line graphs *help* please. (Further Maths)

How would you solve the equation of the line AB in this case, using the
y-y1=m(x-x1) formula?

A(3,-5) B(10,-6)

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I don’t do further maths but I can help.

Find the gradient
Then find what the equation will be
Original post by kittymityyy
How would you solve the equation of the line AB in this case, using the
y-y1=m(x-x1) formula?

A(3,-5) B(10,-6)

I never got taught this way, I always use y= mx + c
Basically find the gradient
So (y2-y1) / (x2 - x1) for the gradient then you can do the rest
Original post by CaptainDuckie
So (y2-y1) / (x2 - x1) for the gradient then you can do the rest

Right!! ty
Original post by Alice.gates
I never got taught this way, I always use y= mx + c
Basically find the gradient


You can rearrange y- y1 = m(x-x1) into the form of y=mx+ c

Once you’ve found the m, which is the gradient
Original post by kittymityyy
Right!! ty


Tell me what you get, (I can’t show you worked solutions or else I’ll get banned) sorry
Original post by kittymityyy
Right!! ty


Original post by CaptainDuckie
You can rearrange y- y1 = m(x-x1) into the form of y=mx+ c

Once you’ve found the m, which is the gradient

so the gradient is -11/7, right?
Original post by CaptainDuckie
Tell me what you get, (I can’t show you worked solutions or else I’ll get banned) sorry

thank you for the help and i got -11/7? is that right? for the gradient
Original post by kittymityyy
so the gradient is -11/7, right?


Not -11/7, do it again
Original post by CaptainDuckie
Not -11/7, do it again

isn't it (-6-5)/(10-3)
Original post by kittymityyy
isn't it (-6-5)/(10-3)


No

y1 is (-5)
Reply 13
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Sinnoh
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Original post by kittymityyy
isn't it (-6-5)/(10-3)


Made a mistake with the negatives. it's - 6 - (-5) which is - 6 + 5, = -1
Original post by CaptainDuckie
No

y1 is (-5)

so -6-(-5)/(10-3) = -1/7?
Original post by kittymityyy
so -6-(-5)/(10-3) = -1/7?


Yes

So substitue into y- y1 = m( x - x1)
Original post by CaptainDuckie
Yes

So substitue into y- y1 = m( x - x1)

oh ok!
Original post by kittymityyy
oh ok!


No problem, you can probably leave it in that form in the exam unless told otherwise...

Remember the gradient equation as (y2-y1)/(x2 -x1)

Memorise it. These questions are naturally reoccurring, (I’m assuming you do AS level Maths too)
Original post by kittymityyy
oh ok!

is it y = -1/7x - 32/7
And don’t get tripped up by the negatives - - makes a plus, rookie mistakes that the examiners love

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