1 TÍnh C = 1.3.5 – 3.5.7 + 5.7.9 – 7.9.11 + … - 97.99.101
Tính C=1.3.5-3.5.7+5.7.9-7.9.11+...-97.99.101
1 TÍnh C = 1.3.5 – 3.5.7 + 5.7.9 – 7.9.11 + … - 97.99.101
mk ko viết đề nhé
C=1.3.5.8 + 3.5.7.8 + 5.7.9.8 + … + 95.97.99.8
C= 1.3.5(7 + 1) + 3.5.7(9 - 1) + 5.7.9(11 - 3) + … + 95.97.99(101 - 93)
C= 1.3.5.7 + 15 + 3.5.7.9 - 1.3.5.7 + 5.7.9.11 - 3.5.7.9 + … + 95.97.99.101 - 93.95.97.99
C= 15 + 95.97.99.101
=>C=\frac{15 + 95.97.99.101}{8}
Tính A = 1.3.5 - 3.5.7 + 5.7.9 - 7.9.11 +...+ 97.99.101
Tính A= 1.3.5 - 3.5.7 + 5.7.9 - 7.9.11 + ....... + 97.99.101
A = 1 . 3 . 5 - 3. 5 . 7 + 5 . 7 . 9 - 7.9.11 + ... + 97.99.101
4A = 1.2.3.4 + 2.3.4.4 + 3.4.5.4 + … + 98.99.100.4
= 1.2.3.4 + 2.3.4(5 - 1) + 3.4.5(6 - 2) + … + 98.99.100(101 - 97)
= 1.2.3.4 + 2.3.4.5 - 1.2.3.4 + 3.4.5.6 - 2.3.4.5 + … + 98.99.100.101 - 97.98.99.100
= 98.99.100.101
=> A = 98.99.25.101
A = 24 497 550
1. TÝnh B = 1.3^2 + 3.5^2 + 5.7^2 + … + 97.99^2
2 C = 1.3.5 – 3.5.7 + 5.7.9 – 7.9.11 + … - 97.99.101
A = \(\frac{2.4.6+4.6.8+6.8.10+8.10.12+...+198.200.202}{1.3.5+3.5.7+5.7.9+7.9.11+...+97.99.101}\) =?
Tính: 1.3.5+3.5.7+5.7.9+...+97.99.101
1.3.5+3.5.7+5.7.9+...+97.99.101
=(101-2).(101-1).101.(101+1):4
=25497450
Tính tổng:
H=1.3.5-3.5.7+5.7.9-7.9.11+...+95.97.99-97.99.101
E=1.33+3.53+5.73+...+49.513
F=1.992+2.982+3.972+...+49.512
tính
B=1.3.5+3.5.7+5.7.9+7.9.11+...+99.101.103