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Linear Equations Question

I'm writing a linear equation given two points.
My points are (0,12) and (10,4).
My question is about the gradient
I know to find the gradient it is m=y2-y1/x2-x1
So, I did m=4-12/10-0 = -8/10 = -4/5
Now, my question is - Is the gradient going to be -4/5 or is it the bottom number aka 5?

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Original post by PinkOneAmong
I'm writing a linear equation given two points.
My points are (0,12) and (10,4).
My question is about the gradient
I know to find the gradient it is m=y2-y1/x2-x1
So, I did m=4-12/10-0 = -8/10 = -4/5
Now, my question is - Is the gradient going to be -4/5 or is it the bottom number aka 5?


The gradient is the ratio ... not the denominator of that ratio.
Original post by RDKGames
The gradient is the ratio ... not the denominator of that ratio.

ummm could u explain more please
Original post by PinkOneAmong
ummm could u explain more please

I am not sure why you would think that 'the bottom number' is the gradient?
Original post by RDKGames
I am not sure why you would think that 'the bottom number' is the gradient?

I watched a youtube video on how to write a linear equation from two co-ords, she said to find the m in y=mx+c you do the equation which I did
When you found m=-4/5, that's the gradient. m is the gradient so you just use that fraction
Original post by PinkOneAmong
I watched a youtube video on how to write a linear equation from two co-ords, she said to find the m in y=mx+c you do the equation which I did

Yes so m = -4/5 in your case. Not 5.
Original post by RDKGames
Yes so m = -4/5 in your case. Not 5.

Okai, thankyou. It's just I watched two videos, the one took the bottom number whereas the other took the fraction so I was a bit lost. So if i turn those co-ords into a full equation how do I find the b? From the video I watched it says to do this -
y=mx+b
12=-4/5(-4/5)+b
12=16/25+b
then to take 16/25 off of both sides so
12-16/25=b

1. I don't understand how to take 16/25 off of 12 and
2. Is that the correct way to work it out or?
Original post by PinkOneAmong
Okai, thankyou. It's just I watched two videos, the one took the bottom number whereas the other took the fraction so I was a bit lost. So if i turn those co-ords into a full equation how do I find the b? From the video I watched it says to do this -
y=mx+b
12=-4/5(-4/5)+b
12=16/25+b
then to take 16/25 off of both sides so
12-16/25=b

1. I don't understand how to take 16/25 off of 12 and
2. Is that the correct way to work it out or?

1. just minus it with a calculator
2. Yes, that gives you the constant "c" and then you can just write it in the form y=mx + c
Original post by ItsStarLordMan
1. just minus it with a calculator
2. Yes, that gives you the constant "c" and then you can just write it in the form y=mx + c

Do I replace the c with the fraction or decimal answer?
Original post by PinkOneAmong
Do I replace the c with the fraction or decimal answer?

m is the fraction as that is the gradient. c is the decimal. do you know what all the letter means in y=mx+c?
Original post by ItsStarLordMan
m is the fraction as that is the gradient. c is the decimal. do you know what all the letter means in y=mx+c?

m=gradient and c = y intercept ?
It depends on what type of gradient the question is asking, if it's the normal then it's -1/gradient, if it's the tangent then it's -(gradient)
So would my final answer be y=-4/5x + 11.36
Original post by PinkOneAmong
So would my final answer be y=-4/5x + 11.36

Exactly! :smile:
I have one last question, to work out b i did
y=mx+b
12=-4/5(-4/5)+b <<<----- For this step, is doing -4/5(-4/5) correct? Should It not be -4/5x1?
12=16/25+b
then to take 16/25 off of both sides so
12-16/25=b
Original post by PinkOneAmong
I have one last question, to work out b i did
y=mx+b
12=-4/5(-4/5)+b <<<----- For this step, is doing -4/5(-4/5) correct? Should It not be -4/5x1?
12=16/25+b
then to take 16/25 off of both sides so
12-16/25=b

ah, my bad. I didn't realise. At that step, you need to sub in the value of x. I see you used coordinates (0,12) as you pute it equal to 12, so x=0 not -4/5. sorry
Original post by ItsStarLordMan
ah, my bad. I didn't realise. At that step, you need to sub in the value of x. I see you used coordinates (0,12) as you pute it equal to 12, so x=0 not -4/5. sorry

so instead would my final b value be 11.2?
Original post by PinkOneAmong
so instead would my final b value be 11.2?

no, but here's a hint
y=12, m=-4/5 and x=0
y=mx+c
Original post by ItsStarLordMan
no, but here's a hint
y=12, m=-4/5 and x=0
y=mx+c

12?

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