# make horizontal curly brace underlying parts of a equation so that I could write another formula under that part of specific equation

how could i make horizontal curly brace underlying parts of a equation so that I could write another formula under that part of specific equation . PS: i do not want to add a text under the curly brace.

Here is my code:

 $\tilde{Y}^I+\tilde{Y}^X = \biggl[\delta_Y \biggl(\Lambda_K \frac{\tilde{K}}{\mu}\biggr)^{-\rho Y} + (1-\delta_Y )(\Lambda^T_l L^F)^{-\rho Y} \biggr]^{-1/\rho Y}-S_{YCZ} \tilde{C}^H - \underbrace{\frac{S_{GCF}}{1-S_{GCF}}\tilde{C}^H}_\text{\tilde{C}^{G}}$


what i want to get : • Well, just write a formula. What is the problem? – Bernard Jan 19 '17 at 12:11
• it doesn't work !!! look at my code , i had used text command to add the formula under the brace !! – haithem Jan 19 '17 at 12:13
• For me it works. Could you post a full code demonstrating the problem? – Bernard Jan 19 '17 at 12:19
• \text is for, well, text. Remove it – egreg Jan 19 '17 at 12:58

You have errors in \underbrace command. Correct is:
\documentclass{article}
$\tilde{Y}^I+\tilde{Y}^X = \biggl[\delta_Y \biggl(\Lambda_K \frac{\tilde{K}}{\mu}\biggr)^{-\rho Y} + (1-\delta_Y )(\Lambda^T_l L^F)^{-\rho Y} \biggr]^{-1/\rho Y}-S_{YCZ} \tilde{C}^H - \underbrace{\frac{S_{GCF}}{1-S_{GCF}}\tilde{C}^H}_{\tilde{C}^{G}}\,,$ 