# (maths) am i doing this right so far?

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#1
am i doing this right? it just looks wrong?
please walk me through what to do from here
i know the picture looks bad but yh lol

i'm just confused i thought it's rearrange then substitute but idk

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1 year ago
#2
No substituting K will not be the correct approach. Try and substitute y = kx/2 + 1 into the first equation.
You will then end up with a quadratic in the first equation.
The question then specifies that they intersect once so can you now see what to do next?
Last edited by Rohan77642; 1 year ago
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#3
so i make them equal to each other and then solve...? Rohan77642

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1 year ago
#4
(Original post by rainclouds-)
so i make them equal to each other and then solve...? Rohan77642

yes make them equal to eachother, make 1 side = 0, solve for K.
for B - since you already have what K is, you can substitute it into the equations
1
1 year ago
#5
(Original post by Rohan77642)
No substituting K will not be the correct approach. Try and substitute y = -kx/2 - 1 into the first equation.
You will then end up with a quadratic in the first equation.
The question then specifies that they intersect once so can you now see what to do next?
Isn't it y = kx/2 + 1?
1
1 year ago
#6
(Original post by rainclouds-)
so i make them equal to each other and then solve...? Rohan77642

Not exactly solve. You now have a quadratic in x. You know that there is only 1 intersection point, therefore that means that there is only one value of x. This means what about a quadratic?
Spoiler:
Show

The quadratic only has 1 solution so use b^2 - 4ac = 0 to find k. Then use the value of k you have found to find x and y for the last part.

Last edited by Rohan77642; 1 year ago
1
1 year ago
#7
(Original post by 3pointonefour)
Isn't it y = kx/2 + 1?
Yes sorry. Corrected.
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1 year ago
#8
(Original post by rainclouds-)
so i make them equal to each other and then solve...? Rohan77642

Sorry, I made a mistake, the substitution should be y = kx/2 + 1
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1 year ago
#9
(Original post by rainclouds-)
am i doing this right? it just looks wrong?
please walk me through what to do from here
i know the picture looks bad but yh lol

i'm just confused i thought it's rearrange then substitute but idk

Basics, pal. There is nothing a ‘mathematical’ about this question. You just make the two equations equal.
1
1 year ago
#10
Umm...

Make y (of the bottom equation) the subject, and you get, y= 1+kx/2.
Then substitute this y in the first equation and work through it.
(Original post by rainclouds-)
am i doing this right? it just looks wrong?
please walk me through what to do from here
i know the picture looks bad but yh lol

i'm just confused i thought it's rearrange then substitute but idk

0
#11
lmaoooo its ok i got it i got the answer

tysm guys free reps 4 all
0
1 year ago
#12
(Original post by rainclouds-)
lmaoooo its ok i got it i got the answer

tysm guys free reps 4 all
You are wrong- none of the replies including mine was on the right path.

The rational as follows

Step 1: You make the two equations equal

Step 2: simplify and organise so you can clearly see what A, B and C are

Step 3: think , in order for a quadratic equation to have only one root (meaning only one solution) the DISCRIMINANT must be 0
Therefore workout the K values that makes the discriminant 0
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#13
(Original post by MathsLove)
You are wrong- none of the replies including mine was on the right path.

The rational as follows

Step 1: You make the two equations equal

Step 2: simplify and organise so you can clearly see what A, B and C are

Step 3: think , in order for a quadratic equation to have only one root (meaning only one solution) the DISCRIMINANT must be 0
Therefore workout the K values that makes the discriminant 0
no i mean i crossed it all out and did the question again. it's alright i'll make a note of it in my book anyway i appreciate the support
0
1 year ago
#14
(Original post by rainclouds-)
no i mean i crossed it all out and did the question again. it's alright i'll make a note of it in my book anyway i appreciate the support
Did you get the idea, though. It doesn’t explicit tell you the discriminant is 0 instead it tells “it intersects at one”
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