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Need help with maths :S

hey I'm having some trouble with my maths hw. Please could you tell me how to get to the answer please?


Solve the equation 21−x=4x2^{1-x}=4^{x}. Got no idea for this one at all

Giving your answers in the form a + b2\sqrt2, where a and b are rational numbers, find
(3−8)2(3-\sqrt8)^{2}. Is this simply 9-8, or 9−229-2\sqrt2?

Thanks alot
Reply 1
Avatar for NancyR
NancyR
Here is an example similar to the first

3^(x +1) = 9^(x)

We know that 9 = 3^2

So we have

3^(x+1) = (3^2)^x

so

3^(x+1) = 3^2x

so x+1=2x
So x = 1

Can you use that to solve Q1
Original post by hdr95
hey I'm having some trouble with my maths hw. Please could you tell me how to get to the answer please?


Solve the equation 21−x=4x2^{1-x}=4^{x}. Got no idea for this one at all

Giving your answers in the form a + b2\sqrt2, where a and b are rational numbers, find
(3−8)2(3-\sqrt8)^{2}. Is this simply 9-8, or 9−229-2\sqrt2?

Thanks alot

Note that 4x=22x4^x=2^{2x}. The powers must be equal.
Reply 3
Avatar for NancyR
NancyR
For the second question remember that (a + b)^2 = (a + b)(a + b) and you need to find all of the bits
Reply 4
Avatar for hdr95
hdr95
OP
Hey can you also help me do this?
223−1−232+1\frac{2\sqrt2}{\sqrt3 -1} - \frac{2\sqrt3}{\sqrt2 + 1}


Do I need to solve each fraction and then subtract them like I would a normal surd?

Thanks
Reply 5
Avatar for hdr95
hdr95
OP
bump.
Reply 6
Avatar for MissBrown
MissBrown
1
Original post by hdr95
bump.


Rationalise each first

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