pi@raspberrypi:~ $ wget https://download-installer.cdn.mozilla.net/pub/firefox/releases/57.0/linux-x86_64/de/firefox-57.0.tar.bz2
--2017-12-17 14:26:11--  https://download-installer.cdn.mozilla.net/pub/firefox/releases/57.0/linux-x86_64/de/firefox-57.0.tar.bz2
Resolving download-installer.cdn.mozilla.net (download-installer.cdn.mozilla.net)... 52.222.252.247
Connecting to download-installer.cdn.mozilla.net (download-installer.cdn.mozilla.net)|52.222.252.247|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 53415219 (51M) [application/x-tar]
Saving to: ‘firefox-57.0.tar.bz2’

firefox-57.0.tar.bz 100%[=====================>]  50.94M   279KB/s   in 6m 40s 

2017-12-17 14:32:51 (131 KB/s) - ‘firefox-57.0.tar.bz2’ saved [53415219/53415219]

pi@raspberrypi:~ $ tar -xjf firefox-57.0.tar.bz2
pi@raspberrypi:~ $ sudo mv firefox /opt/firefox57
pi@raspberrypi:~ $ sudo mv /usr/bin/firefox /usr/bin/firefoxold
pi@raspberrypi:~ $ sudo ln -s /opt/firefox57/firefox-bin /usr/bin/firefox
pi@raspberrypi:~ $ firefox
bash: /usr/bin/firefox: cannot execute binary file: Exec format error