Need help with two questions (1 Viewer)

[BlueGas]

 

[Ambility]

For (7), you should be looking at both the square root sign and the denominator. Dividing by zero is not allowed, and taking the square root of a negative number is not allowed. So let's think about the domain you can't have in this function. x can not be 2, because then the denominator is 2-2=0 and we can't have that. Next we need to find where the expression under the radicle sign is positive or zero.

 

[davidgoes4wce]

Q5.

 

[BlueGas]

For (7), you should be looking at both the square root sign and the denominator. Dividing by zero is not allowed, and taking the square root of a negative number is not allowed. So let's think about the domain you can't have in this function. x can not be 2, because then the denominator is 2-2=0 and we can't have that. Next we need to find where the expression under the radicle sign is positive or zero.

Okay so basically it's between A and D? C is wrong from your explanation, and B isn't really an answer, so what do I do now?

 

[BlueGas]

Q5.

What happened to e and ln in the second step?

 

[davidgoes4wce]

Q7.

 

[qwert73]

What happened to e and ln in the second step?

e^lnx = x
try it in your calculator

 

[BlueGas]

Q7.

So from your working out, the answer is B, but the actual answer is C, I want to know how though.

 

[qwert73]

I think the answer for 7 is c as all the other options create a zero on the denominator which you can't have

 

[davidgoes4wce]

In the 2nd step, its based on the power rules.

Power rule
ln(x^y) = y ∙ ln(x)

http://formulas.tutorvista.com/math/natural-log-formula.html

 

[D94]

What happened to e and ln in the second step?

Clearly you need to learn logarithms again. There's no point doing a question like this without understanding the fundamentals.

 

[InteGrand]

For 7, the answer will be the set of values of x such that the radicand (expression inside the radical (the square root)) is non-negative.

 

[davidgoes4wce]

My answer for Q7 is wrong. It's been a long day.

 

[davidgoes4wce]

The answer should be C

 

[Ambility]

Q7.

You've only considered where the denominator is equal to zero. The expression under the square root must be also greater than or equal to zero.

 

[Ambility]

For 7, the answer will be the set of values of x such that the radicand (expression inside the radical (the square root)) is non-negative.

But you also need to consider that the denominator in the radicand can not be equal to zero.

 

[qwert73]

But you also need to consider that the denominator in the radicand can not be equal to zero.

this is how you answer the questions. Every answer a part from C has the option of making the denominator = 0 which you can't have, therefor C is the only possible option.

 

[Ambility]

this is how you answer the questions. Every answer a part from C has the option of making the denominator = 0 which you can't have, therefor C is the only possible option.

Yeah, sometimes deductive reasoning > inductive reasoning.

 

[InteGrand]

But you also need to consider that the denominator in the radicand can not be equal to zero.

That is already accounted for by taking the set of values such that the radicand is non-negative, since these values don't include values of x where the radicand has 0 denominator.