" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2024 KUDO.TIPS - All rights reserved.
Un = Sn - S(n-1)
Un = 4n² (n+1) - 4(n-1)²(n)
Un = 4n³ + 4n² - 4n³ + 8n² - 4n
Un = 12n² - 4n
U4 = 12(4²) - 4(4) = 11 × 16 = 176