Lời giải:
$S=4+12+36+108+....+972+2916$
$3\times S=12+36+108+324+...+2916+8748$
$3\times S-S=(12+36+108+324+...+2916+8748)-(4+12+36+108+....+972+2916)$
$2\times S=8748-4=8744$
$S=8744:2=4372$
4 +12+36+108+...+2916 .
Tính: 1/4+1/12+1/36+.....+1/2916
1/4+ 1/12 + 1/36+ 1/108+....+ 1/2010 + 1/6030
9×4×101+108×21-61×36
9×4×101+108×21-61×36
\(\frac{1}{4}+\frac{1}{12}+\frac{1}{36}+\frac{1}{108}+...+\frac{1}{2010}+\frac{1}{6030}\)
Tính giá trị biểu thức
A=1/4+1/12+1/36+1/108+1/324+1/972
B=1/2+5/6+11/12+19/20+29/30+41/42+55/56
9×4×101+108×21-61×36
[ 2+ 4 + 6 + ...+ 240 ] * [ 111 * 108 - 36 *333]
( 2 + 4 + 6 +...+100 ) * (36 * 333 -108 * 111)
