10 34/81
Объяснение:
Sₙ=b₁·(1-qⁿ)/(1-q)
S₅=4·(1-(2/3)⁵)/(1 -2/3)=4·(1 -32/243)/(3/3 -2/3)=4·(243/243 -32/243)/(1/3)=4·3·211/243=4·211/81=844/81=10 34/81
10 34/81
Объяснение:
Sₙ=b₁·(1-qⁿ)/(1-q)
S₅=4·(1-(2/3)⁵)/(1 -2/3)=4·(1 -32/243)/(3/3 -2/3)=4·(243/243 -32/243)/(1/3)=4·3·211/243=4·211/81=844/81=10 34/81