Stuck on maths questions

iloading22

6

Can anyone help me on these two questions, I can't seem to get an answer.

Thanks!

What you have done so far in terms of working?

Reply 2

assassinjeev22

14

you for b (the solve one) try take logs of both sides with base 3. Then rearrange to get x,

Hint for A - substitute the value of A into A^2

Hint for B - (AB)^2 - the squared effects both terms

Hints in general
When the squared is outside the bracket so say (Ax)^2, the squared will affect the A and the x leaving you with A^2x^2,

Hope this helps! I'll be happy to help if you have any further questions

Reply 3

ManLike007

19

Original post by iloading22

Can anyone help me on these two questions, I can't seem to get an answer.

Thanks!

Part b, multiply both sides by

ln

or

log

. Use the law

ln(a)^{b} \equiv b \cdot ln(a)

to help you simplify and rearrange.

Part a, if

A=\frac{1}{5}x^{2}

then

A^{2} = (\frac{1}{5}x^{2})^{2}

. Use the rule

(ab)^{n} \equiv a^{n}b^{n}

Part b,

(AB)^{2} \equiv (A \cdot B)^{2} \Rightarrow (\frac{1}{5}x^{2} \cdot \sqrt5 x^{-\frac{1}{2}})^{2}

. I've just substituted in A and B, that's all because you know that

A=\frac{1}{5}x^{2}

and

B=\sqrt5 x^{-\frac{1}{2}}

.
Use the rule

a^{m} \cdot a^{n} \equiv a^{m+n}

to help you simplify!

(edited 6 years ago)

Reply 4

BobLoblawLawBlog

16

I think the others are making (b) sound more complicated than it is. I'm assuming you won't have even covered logs yet given what the next question is.

Write sqrt(3) as 3^0.5, and write 81 as a power of 3. You can then use the rules of indices to simplify this so that you can directly compare it to the left hand side

(edited 6 years ago)

Reply 5

Dat1Guy

16

Original post by BobLoblawLawBlog

I think the others are making (b) sound more complicated than it is. I'm assuming you won't have even covered logs yet given what the next question is.

Write sqrt(3) as 3^0.5, and write 81 as a power of 3. You can then use the rules of indices to simplify this so that you can directly compare it to the left hand side

I agree, that would probably be the easiest way of solving it!

Reply 6

iloading22

OP

6

Original post by BobLoblawLawBlog

I think the others are making (b) sound more complicated than it is. I'm assuming you won't have even covered logs yet given what the next question is.

Write sqrt(3) as 3^0.5, and write 81 as a power of 3. You can then use the rules of indices to simplify this so that you can directly compare it to the left hand side

I ended up getting x = -6, is this correct?

Reply 7

sivthasan

14

Original post by iloading22

I ended up getting x = -6, is this correct?

Spoiler

Reply 8

BobLoblawLawBlog

16

Original post by iloading22

I ended up getting x = -6, is this correct?

Try substituting it back in and tell me if both sides then give the same answer.

Reply 9

ManLike007

19

Original post by iloading22

I ended up getting x = -6, is this correct?

Close but no.

I just realised as the user above said you may have not covered logs yet, you can put both sides to a base of 3, I'll show you what BobLoblawLawBlog means. Left hand side is already done.

So,