tolong dijawab ya tolong
• U1 = 5
b = 4
• U25 = 146
Penjelasan dengan langkah-langkah:
• U1 = S1
Un = S(n) - S(n-1)
Sn = 2n² + 3n
U1 = S1 = 2 x 1² + 3 x 1
= 2 + 3
= 5
U2 = S2 - S1
= 2 x 2² + 3 x 2 - S1
= 8 + 6 - 5
= 9
b = U2 - U1 = 9 - 5 = 4
• Sn = 3n² - n
U25 = S25 - S24
= (3 x 25² - 25) - (3 x 24² - 24)
= (3 x 625 - 25) - (3 x 576 - 24)
= (1875 - 25) - (1728 - 24)
= 1850 - 1704
= 146
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