tính nhanh :54/1x3x7 + 54/3x7x9 + 54/7x9x13 + 54/9x13x15
Giúp mình nhé! THANKS
\(\frac{6}{1x3x7}+\frac{6}{3x7x9}+\frac{6}{7x9x13}+\frac{6}{9x13x15}+\frac{6}{13x15x9}\)
\(\frac{6}{1\times3\times7}+\frac{6}{3\times7\times9}+\frac{6}{7\times9\times13}+\frac{6}{9\times13\times15}+\frac{6}{13\times15\times9}\)
\(=\frac{1}{1\times3}-\frac{1}{3\times7}+\frac{1}{3\times7}-\frac{1}{7\times9}+\frac{1}{7\times9}-\frac{1}{9\times13}+\frac{1}{9\times13}-\frac{1}{13\times15}+\frac{1}{13\times15}-\frac{1}{15\times9}\)
\(=\frac{1}{1\times3}-\frac{1}{15\times9}=\frac{1}{3}-\frac{1}{135}=\frac{45}{135}-\frac{1}{135}=\frac{44}{135}\)
6/1x3x7 + 6/3x7x9 + 6/9x13x15 + 6/13x15x19
tính nhanh nha mn
6/1x3x7 + 6/3x7x9 + 6/9x13x15 + 6/13x15x19
tính nhanh nha mn
6/1x3x7 + 6/3x7x9 + 6/9x13x15 + 6/13x15x19
tính nhanh nha mn
6/1x2x7+6/3x7x9+6/7x9x13+6/9x13x15+6/13x15x19
cứu tui câu này đi
tính nhanh
1+5+7+48+5+2+5+5+566+54+4+4+54+54=???
TÍNH NHANH:
A= 72 + 139 + 195 + 216
B=54 x 63 + 54 x 67 - 54 x 40
A = 72+139+195+216
=622
B=54 x 63 + 54 x 67 - 54 x 40
= 54 x ( 63+67-40)
= 54 x 90 = 4860
A=72+139+195+216
A=(72+139)+(195+216)
A=211+411)
A=622
B=54x63+54x67-54x40
B=54x(63+67-40)
B=54x90
4860
Tính nhanh :
54 x 41 x 54 x 12 =..........
54 x 41 x 54 x 12
=2214x648
=1434672
54x41x54x12
=54x(41x12)
=54x192
=10368
tick nha!!!!
tính nhanh: 50 x ( 54 - 100) + 54 x ( 50 + 100 )