Core 1 Surds help please!

Basically the question is
Two lines have equations
Y=root2 x+9
y=10-x
I know you do root2 x+9=10-x,
Then you get root2+2x=1
2x=1-root2
And i get x=1-root2/2
The answer should just be x=1-root2
Where did igo wrong?
Thanks :smile:

Reply 1

ViralRiver

I think the answer is actually

x=\sqrt{2}-1

.

I'm not going to show you all the steps, but the first few so you can see where you've gone wrong:

10-x = \sqrt{2} x+9

1 = x + \sqrt{2} x

1 = x(1+\sqrt{2})

Reply 2

mamma_mia123

Original post by ViralRiver

I think the answer is actually

x=\sqrt{2}-1

.

I'm not going to show you all the steps, but the first few so you can see where you've gone wrong:

10-x = \sqrt{2} x+9

1 = x + \sqrt{2} x

1 = x(1+\sqrt{2})

After that would you do x-1=root2+1?

Reply 3

TenOfThem

Original post by mamma_mia123

After that would you do x-1=root2+1?

no

the x is times the bracket so you need to divide

Reply 4

mamma_mia123

Original post by TenOfThem

no

the x is times the bracket so you need to divide

So its 1/x=root2+1
then what?

Reply 5

TenOfThem

Since you want x on its own you would divide by the bracket so that you have x =

Then you need to rationalise the denominator

Reply 6

mamma_mia123

Original post by TenOfThem

Since you want x on its own you would divide by the bracket so that you have x =

Then you need to rationalise the denominator

Thanks, i actually forgot whqt i was trying to find :smile:

btw, i you had 4root6pi/4, could you cancel down to root6pii (pi root 6)?

Reply 7

ViralRiver

Original post by mamma_mia123

Thanks, i actually forgot whqt i was trying to find :smile:

btw, i you had 4root6pi/4, could you cancel down to root6pii (pi root 6)?

If you're asking whether

\frac{4\pi\sqrt{6}}{4} = \pi\sqrt{6}

, then yes it does.

(edited 12 years ago)

Reply 8

mamma_mia123

Original post by ViralRiver

If you're asking whether

\frac{4\pi\sqrt{6}}{4} = \pi\sqrt{6}

, then yes it does.

Hello, would 1/4 x2 multiplied by x2=1/4 x4?

Reply 9

ViralRiver

Original post by mamma_mia123

Hello, would 1/4 x2 multiplied by x2=1/4 x4?

Not sure what you're asking, unless you mean

\frac{1}{4}\times 2\times 2=\frac{1}{4} \times 4=\frac{4}{4}=1

, in which case you're right :smile:

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Core 1 Surds help please!

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