# Obtain a equation from operational amplifiers

#### Doppler2902

Joined Sep 15, 2020
37
Hi guys, I nedd to obtain the following equation from operational amplifiers:

So, what I thought is use two inverting operational amplifiers for get the gain and a voltage divider, but I'm not sure of the procedure, it's right? Thanks for the help

#### Ramussons

Joined May 3, 2013
1,374
Look at it this way:

Can be expanded to V1/2* [ 1-33/56] => V1/2 * [- 23/56]
A single Opamp with the 1/2 divider at the input and 56 K / 23 K for the feedback and input

What say?

#### ericgibbs

Joined Jan 29, 2010
18,251
hi Ramussons.
This is a Homework question, please hints and guidance only, no final solution.

Mod:

#### Ian0

Joined Aug 7, 2020
8,947
Doesn't the 1+ suggest that it should be non-inverting amplifier, and possibly the 33/56 suggest a ratio of two resistors (as they are both E12 values)?
. . .but then there's the minus sign.

#### dcbingaman

Joined Jun 30, 2021
1,065
Look at it this way:

Can be expanded to V1/2* [ 1-33/56] => V1/2 * [- 23/56]
A single Opamp with the 1/2 divider at the input and 56 K / 23 K for the feedback and input

View attachment 260495
What say?
There is a mistake in that math: 1-33/56=>23/56 (Positive) at 1/2 => 23/112. Two resistors and an amp is all you need. Can't say more without providing a solution.

Last edited:

#### Ramussons

Joined May 3, 2013
1,374
hi Ramussons.
This is a Homework question, please hints and guidance only, no final solution.

Mod:
My mistake.
Missed the header in my hurry.