Is that answer correct? 5/+81.87* (4-j3+(3sqrt[2]/-45*)/(7-j1))

[oscaro]

\(\displaystyle 5\,\,\underline{\diagup +81.87^{\circ}}\, \left(4\, -\, j3\, +\, \dfrac{3\, \sqrt{\strut 2\,}\, \underline{\diagup -45^{\circ}}}{7\, -\, j1}\right)\)

\(\displaystyle \mbox{Answer: }\, 88.162\, \underline{\diagup 30.127^{\circ}}\, =\, 76.2520\, +\, j44.2506\)

Is that answer correct?

 

[tkhunny]

Why don't you show us YOUR workings and you tell us if it's correct.

 

[stapel]

\(\displaystyle 5\,\,\underline{\diagup +81.87^{\circ}}\, \left(4\, -\, j3\, +\, \dfrac{3\, \sqrt{\strut 2\,}\, \underline{\diagup -45^{\circ}}}{7\, -\, j1}\right)\)

\(\displaystyle \mbox{Answer: }\, 88.162\, \underline{\diagup 30.127^{\circ}}\, =\, 76.2520\, +\, j44.2506\)

Is that answer correct?

What where the instructions? What does the "forward-slash--underline" notation mean?

Thank you!

 

[oscaro]

Then istruction is just to simplify the complex expresion to a polar expression. Please see the attached image on original post, the other was added by moderator

 

[oscaro]

Why don't you show us YOUR workings and you tell us if it's correct.

to me it is 19.8+19.7i

 

[stapel]

to me it is 19.8+19.7i

Is it supposed to be "j" or "i"? Either way, for what does this stand? Do the numbers that follow "j" in the original exercise stand for superscripts (that is, exponents), subscripts, or (as written) multipliers? What operation does the "forward-slash--underline" notation indicate?

What do you mean by "complex expression"? Does this indicate that you're actually working with a "complex number" which you're needing to "convert" to "polar form"? (here)

Please be complete. Thank you!

 

[oscaro]

I ll transcript the instruction from the book:

Determine the polar and rectangular form of the expression:

 

[oscaro]

This is directly from the book, cannot explain any further

 

[oscaro]

Maybe I wasn't clear, sorry. I am not asking to review my calculation. The answer posted is the book's. So I am askinkg to check the book's answer because i think its wrong, and that is not expectable or acceptable from a well known book

 

[tkhunny]

Show us your intermediate results. Don't make us guess what you are doing.

Explain the Phasor notation, for example.

 

[mmm4444bot]

I am asking [others] to check the book's answer because i think [it's] wrong, and that is not expectable (sic) or acceptable from a [well-known book.]

I agree that it's not good, when math texts contain errors. However, I've seen enough math texts to be able to say, "Expect errors in your math text because there's no such thing as a perfect book. All math texts contain errors; everybody needs to deal with this fact." :cool:

 

[stapel]

Maybe I wasn't clear, sorry. I am not asking to review my calculation. The answer posted is the book's. So I am askinkg to check the book's answer because i think its wrong, and that is not expectable or acceptable from a well known book

Okay. As mentioned a few times now, we don't know what you're doing, what the instructions might have been, nor what your notation means. Until you tell us what's going on here, there is no way for us to even guess whether or not it's correct.

Please reply with the requested information. Thank you!

 

[tkhunny]

It is quite acceptable to find errors. Publishing is not magic. If you believe it to be wrong, then fix it and move on.

Quickly checking just the magnitude \(\displaystyle 5\cdot\left(5 + \dfrac{3\sqrt{2}}{\sqrt{50}}\right) = 28\) Is that consistent with your result or the books or neither?

 

[Deleted member 4993]

\(\displaystyle 5\,\,\underline{\diagup +81.87^{\circ}}\, \left(4\, -\, j3\, +\, \dfrac{3\, \sqrt{\strut 2\,}\, \underline{\diagup -45^{\circ}}}{7\, -\, j1}\right)\)\(\displaystyle \mbox{Answer: }\, 88.162\, \underline{\diagup 30.127^{\circ}}\, =\, 76.2520\, +\, j44.2506\)Is that answer correct?

I am not familiar with the notation used. But looking at the answer suggests:
\(\displaystyle 88.162\, \underline{\diagup 30.127^{\circ}} \, =88.162[cos(30.127) + sin(30.127)]\)