Question Number 11580 by Nayon last updated on 28/Mar/17
$${why}\:\frac{{dy}}{{dx}}=\frac{{dy}}{{du}}.\frac{{du}}{{dx}} \\ $$
Answered by mrW1 last updated on 28/Mar/17
$${the}\:{chain}\:{rule}\:{is}\:{one}\:{of}\:{the}\:{elementary} \\ $$$${rules}.\:{you}\:{should}\:{know}\:{them},\:{but}\:\: \\ $$$${you}\:{don}'{t}\:{need}\:{to}\:{prove}\:{them}.\:{if} \\ $$$${you}\:{want}\:{to}\:{know}\:{their}\:{proof},\:{it}'{s}\:{better} \\ $$$${when}\:{you}\:{consult}\:{a}\:{book}\:{or}\:{wikipedia} \\ $$$${for}\:{more}\:{details}. \\ $$