Tinh B=1+1/2*(1+2)+1/3*(1+2+3)+1/4*91+2+3+4)+.........+1/20*(1+2+3+...+20)
Tinh P giup minh voi : P = 1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/16(1+2+3+...+16) . Ban nao lam duoc thi giup minh nha . Minh se tick ung ho .
a)Chứng minh rằng :1/6<1/5^2+1/6^2+1/7^2+...+1/100^2<1/4
b)tính tổng :(-3)^0+(-3)^1+(-3)^2+...+(-3)^20
Tính B= 1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/20(1+2+3+...+20)
Tính B=1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/20(1+2+3+...+20)
tính B=1+1/2*(1+2)+1/3*(1+2+3)*1/4*(1+2+3+4)+...+1/20*(1+2+3+...+20)
B = 1+ 1/2 ( 1+2) + 1/3 ( 1+2+3) + 1/4 ( 1+2+3+4) +...+ 1/20( 1+ 2+3+...+ 20)
tính hợp lý
B=1+1/2.(1+2)+1/3.(1+2+3)+1/4.(1+2+3+4)+....+1/20.(1+2+3+...+20)
tính : B=1+1/2 (1+2) + 1/3(1+2+3)+....+1/20(1+2+3+4+....+20)