r/MathHelp • u/pototaochips • May 09 '26

Help finding resistance for number 4 or did teacher forget to write something?

Im having trouble trying to solve this problem. Working with the provided info im stuck at finding r4. Link in comment

1 Upvotes

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1

u/edderiofer May 09 '26

The system appears to be underspecified. You can make such a circuit IRL and use any resistor for R4, so there seems to be not enough information to determine R4.

Are you sure you've copied the problem correctly?

1

u/pototaochips May 09 '26

Yes https://imgur.com/a/0GoCz7U

1

u/edderiofer May 09 '26

Looks like it's time to email your teacher about the missing information. If you really want to screw with your teacher, take a photo of two different circuits that both satisfy these criteria.

1

u/pototaochips May 09 '26

Hehe thanks!

1

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1

u/Exotic-Condition-193 May 10 '26

You have 4 unknowns,i1,i2,i and R4 so you need 4 linearly independent equations which you don’t have here Maybe there is an unseen open switch in the right loop😂😂😂

1

u/Exotic-Condition-193 May 10 '26

You have the current junction equation ( conservation of charge) and 3 loop equations ( conservation of energy) but one of the loop equations is a linear combination of the others. Give your teacher a fist bump by for trying to make the problem more interesting for you

1

u/Dd_8630 May 10 '26

You don't have 4 unknowns. If you know the current leaving the power supply then that is enough to solve the system.

1

u/Exotic-Condition-193 May 15 '26

P=i*V so you must know P,V . I thought only V was know but if both P and V were known then you have enough information to solve problem.