cho A = -4/5 + 4/5^2 - 4/5^3 + ......+ 4/5^200
tính
TÍNH TỔNG:
a)A=3-3^2+3^3-3^4+...+3^99-3^100
b)B=-(4/5)+4/5^2-4/5^3+...-4/5^199+4/5^200
Tính nhẩm:
a) 2 x 2 = ...... 3 x 3 = ......
2 x 4 = ...... 3 x 5 = ......
2 x 6 = ...... 3 x 7 = ......
2 x 8 = ...... 3 x 9 = ......
4 x 4 = ...... 5 x 5 = ......
4 x 2 = ...... 5 x 7 = ......
4 x 6 = ...... 5 x 9 = ......
4 x 8 = ...... 5 x 3 = ......
b) 200 x 4 = ...... 300 x 2 = ......
200 x 2 = ...... 300 x 3 = ......
400 x 2 = ...... 500 x 1 = ......
100 x 4 = ...... 100 x 3 = ......
a) 2 x 2 = 4 3 x 3 = 9
2 x 4 = 8 3 x 5 = 15
2 x 6 = 12 3 x 7 = 21
2 x 8 = 16 3 x 9 = 27
4 x 4 = 16 5 x 5 = 25
4 x 2 = 8 5 x 7 = 35
4 x 6 = 24 5 x 9 = 45
4 x 8 = 32 5 x 3 = 15
b) 200 x 4 = 800 300 x 2 = 600
200 x 2 = 400 300 x 3 = 900
400 x 2 = 800 500 x 1 = 500
100 x 4 = 400 100 x 3 = 300
Trả lời 1 câu thôi nhé em 100 nhân 4 bằng 400 nhá em
a) 2 x 2 =4 ...... 3 x 3 = ..9....
2 x 4 = ....8.. 3 x 5 = ...15...
2 x 6 = ....12.. 3 x 7 = .21.....
2 x 8 = ..16.... 3 x 9 = ..27....
4 x 4 = ...16... 5 x 5 = ...25...
4 x 2 = ...8... 5 x 7 = ..35....
4 x 6 = .....24. 5 x 9 = .45.....
4 x 8 = ..32.... 5 x 3 = .15.....
b) 200 x 4 = 800...... 300 x 2 =600 ......
200 x 2 = ..400.... 300 x 3 = 900......
400 x 2 = .....800. 500 x 1 = ..500....
100 x 4 = ....400.. 100 x 3 = .300.....
Cho A=2×9×8+3×12×10+4×15×12+...+98×297×200/23×4+3×4×5+4×5×6+..+98×99×100
Tính a2
tính tổng
B= 7-7 mu 4 + 7 mu 4 -........+7 mu 301
A = 1 + 5 mũ 2 + 5 mu 4 + 5 mu 6 +.....+5 mu 200
tính
A= 1/7+1/7mu 2 + 1/7 mu 3+......+1/7mu 100
B=-4/5+4/5 mu 2 - 4/5 mu 3 + ....+4/5mu 200
tính A=25 mũ 8 + 25 mũ 4 + 25 mu 20 +......+25 mu 4 +1 / 25 mu 20 + 25 mu 28 + 25 mu 26 +.....= 25 mu 2 +1
7 × 3 mu x + 20 × 3 mu x = 3 mu 25
tính gọn:
A=2+2^2+2^3+2^4+.....+2^200
B=1+3+3^2+3^2+.....+2007
C=4+4^2+4^3+4^4+...+4^100
D=5+5^2+5^3+....+5^150
a)
A = 2 + 22 + 23 + 24 + ... + 2200
2A = 22 + 23 + 24 + 25 + ... + 2200
2A - A = A = 2200 - 2
b) chịu
c)
C = 4 + 42 + 43 + 44 +... + 4100
4C = 42 + 43 + 44 + 45 + ... + 4101
4C - C = 3C = 4101 - 4
\(\Rightarrow\) C = \(\frac{4^{101}-4}{3}\)
d)
D = 5 + 52 + 53 + ... + 5100
5D = 52 + 53 + 54 + ... + 5101
5D - D = 4D = 5101 - 5
\(\Rightarrow\)D = \(\frac{5^{101}-5}{4}\)
Tính
A = 4 + 4 mũ 4 + 4 mũ 7 + .....+4 mũ 31
B = 5 mũ 2 + 5 mũ 4 + 5 mũ 6 + ..... + 5 mũ 200
C = 8 + 8 mũ 3 + 8 mũ 5 + .... + 8 mũ 35
A = 4 + 44 + 47 + ... + 431
43A = 43.(4 + 44 + 47 + ... + 431)
64A = 44 + 47 + 410 + ... + 434
64A - A = (44 + 47 + ... + 434) - (4 + 44 + ... + 431)
63A = 434 - 4
=> A = \(\frac{4^{34}-4}{63}\)
Tính \(B=-\frac{4}{5}+\frac{4}{5^2}-\frac{4}{5^3}+...+\frac{4}{5^{200}}\)
\(-5B=4-\frac{4}{5}+\frac{4}{5^2}-....-\frac{4}{5^{199}}\)
\(-5B-B=4-\frac{4}{5^{200}}\)
\(-6B=\frac{4\left(5^{200}-1\right)}{5^{200}}\)
\(B=\frac{2\left(1-5^{200}\right)}{5^{200}.3}\)
Ta có:\(B=...\)
\(\Leftrightarrow5B=-4+\frac{4}{5}-\frac{4}{5^2}+...+\frac{4}{5^{199}}\)
\(\Leftrightarrow5B+B=-4+\frac{4}{5^{200}}\)
\(\Leftrightarrow6B=-4+\frac{4}{5^{200}}\Rightarrow B=\frac{-4+\frac{4}{5^{200}}}{6}=\frac{-2+\frac{2}{5^{200}}}{3}\)
haỹ tính những giá trị sau
A=3^2+3^3+3^4+...+3^100
B=4^200-4^198+4^196-...-4^4+4^2-4
C=5^50-5^48+5^46-...-5^4+5^2-5
D=3^99-3^96+3^93-...+3^3-3^1
E=5^99-5^96+5^93-...+3^3-3^1
F=3^50-3^48+3^46-...-3^4+3^2-3
A= (-4/5)+(4/52)+(4/53)+...+(4/5200) = ?