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Mathematics 7 Online
OpenStudy (anonymous):

I have the answers .. but can someone explain how to get them? Thank you xx

OpenStudy (anonymous):

OpenStudy (anonymous):

So you have to solve for \(x\) then?

OpenStudy (anonymous):

d. x=1.69 e.x=3.68 f. x=42.88 g. x=32 h. x=18.99 i=58.72

OpenStudy (anonymous):

yes the directions say to solve for x

OpenStudy (anonymous):

You have to change the expression into a simple fractional exponent. Something of the form \(x^{a/b}\). Then you take both sides to the power of \(b/a\). This will isolate \(x\).

OpenStudy (anonymous):

for example for d what would I raise?

OpenStudy (anonymous):

For \(d\), we can see \[ \frac{1}{\sqrt{x}} = \frac{1}{x^{1/2}}=x^{-1/2} \]Now the reciprocal of \(-1/2\) is going to be \(-2/1 = -2\).

OpenStudy (anonymous):

Thus \[ \left(\frac{1}{\sqrt{x}}\right)^{-2}=x=(0.77)^{-2} \]

OpenStudy (anonymous):

ok I see now :) thanks so much so for e what would i have to do since theres 8 in the root

OpenStudy (anonymous):

Use \[ \sqrt[b]{x^a} = x^{a/b} \]

OpenStudy (anonymous):

Remember that \(\sqrt{x} = \sqrt[2]{x}\)

OpenStudy (anonymous):

You also need to use \(\frac{1}{x^a}=x^{-a}\)

OpenStudy (anonymous):

so -2/3?

OpenStudy (anonymous):

Well, there is no negative in d.

OpenStudy (anonymous):

whoops, I mean no negative in e. We had one in d because it was a fraction.

OpenStudy (anonymous):

I don't really understand how to do e. I looked at the rules but I didn't understand :/

OpenStudy (anonymous):

Okay for e, we have to do it one at a time.

OpenStudy (anonymous):

\[ \sqrt{8x^3}=(8x^3)^{1/2} \]So first we do both sides to the power of \(2\).

OpenStudy (anonymous):

\[ 8x^3 = (20)^2 = 400 \]

OpenStudy (anonymous):

Then we divide by \(8\): \[ x^3= 400/8=50 \]

OpenStudy (anonymous):

Now we do reciprocal of \(3\) which is \(1/3\) \[ x = (50)^{1/3} \]

OpenStudy (anonymous):

oh ok i see now:))) so for f-i are they the same method?

OpenStudy (anonymous):

Yes.

OpenStudy (anonymous):

When you isolate the variable, you generally get rid of things opposite of the order of operations. Thus exponents are the last part to get rid of.

OpenStudy (anonymous):

for f is would be 1/3 since we don't touch the exponent?

OpenStudy (anonymous):

What do you mean?

OpenStudy (anonymous):

because i think you would need to subtract 18 and 32 -18 is 14 so i'm kinda stuck from there

OpenStudy (anonymous):

Yes, then you get rid of the \(4\) next.

OpenStudy (anonymous):

Then you can get rid of the power after that.

OpenStudy (anonymous):

to get rid of the 4 can i just divide it or do i do the reciprocal?

OpenStudy (anonymous):

You are dividing. Which is actually the same as multiplying by the reciprocal.

OpenStudy (anonymous):

You can divide by \(4\) or multiply by \(1/4\). Both work.

OpenStudy (anonymous):

how would the power of 3 work though

OpenStudy (anonymous):

Well, you have \(x^{1/3}\). The reciprocal is \(3\).

OpenStudy (anonymous):

but 14 to the exponent of 1/3 isn't 42.88 that's where i'm kinda lost

OpenStudy (anonymous):

it's just the 1/4 and the 1/3 are confusing me

OpenStudy (anonymous):

lmao @lilliegirl's profile pic looks like the pic from the song "marl1"

OpenStudy (anonymous):

lool

OpenStudy (anonymous):

does anyone know how to do f? I'm seriously stuck

OpenStudy (whpalmer4):

\[4\sqrt[3]{x}+18=32\]Subtract 18 from both sides.\[4\sqrt[3]{x}=14\]Divide both sides by 4.\[\sqrt[3]{x}=\frac{7}{2}\]Raise both sides to the 3rd power.\[x=(\frac{7}{2})^3 \]

OpenStudy (whpalmer4):

Or if you prefer: \[4\sqrt[3]{x} = 14\]Raise both sides to 3rd power.\[64x=2744\]\[x=\frac{343}{8}\]

OpenStudy (anonymous):

thank you so much for helping everything.. I really appreciate it!

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