# Linear Equations Question

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#1
I'm writing a linear equation given two points.
My points are (0,12) and (10,4).
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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1 year ago
#2
(Original post by PinkOneAmong)
I'm writing a linear equation given two points.
My points are (0,12) and (10,4).
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.
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#3
(Original post by RDKGames)
The gradient is the ratio ... not the denominator of that ratio.
ummm could u explain more please
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1 year ago
#4
(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?
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#5
(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
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1 year ago
#6
When you found m=-4/5, that's the gradient. m is the gradient so you just use that fraction
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1 year ago
#7
(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.
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#8
(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?
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1 year ago
#9
(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
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#10
(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?
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1 year ago
#11
(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?
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#12
(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 ?
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1 year ago
#13
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)
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#14
So would my final answer be y=-4/5x + 11.36
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1 year ago
#15
(Original post by PinkOneAmong)
So would my final answer be y=-4/5x + 11.36
Exactly! 0
#16
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
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1 year ago
#17
(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
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#18
(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?
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1 year ago
#19
(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
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#20
(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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