Warning: file_get_contents(https://ojs.journalbusiness.my/ojs.php): failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /var/www/ojs.unud.ac.id_backup/lib/pkp/includes/functions.inc.php on line 4 Murti, A.S., Manuaba, I.B.G., AND Arjana, I.G.D. " OPTIMASI UNIT PLTU BERBAHAN BAKAR BATUBARA MENGGUNAKAN METODE LAGRANGE DI PT. INDONESIA POWER UP SURALAYA" Jurnal SPEKTRUM [Online], Volume 7 Number 1 (7 March 2020)