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समांतर श्रेणी

Question
CBSEHHIMAH10010256

एक A.P. में,
a = 3, n = 8 और S = 192 दिया है। d ज्ञात कीजिए।

Solution

यहाँ, a = 3, n = 8
S = 192  
straight S subscript straight n space equals space straight n over 2 space left square bracket space 2 straight a space plus space left parenthesis straight n space minus space 1 right parenthesis space straight d space right square bracket
therefore space 192 space equals space 8 over 2 space left square bracket space 2 space cross times space 3 space plus space left parenthesis space 8 space minus space 1 space right parenthesis space straight d space right square bracket
rightwards double arrow space 192 over 4 space equals space 6 space plus space 7 straight d
rightwards double arrow 6 +7d = 48
rightwards double arrow space straight d space equals space 42 over 7 space equals space 6
अत:, d = 6