2.2:2.2:2.2:2.2= ...................
2.2..2.2..2.2..2.2..2.2..2.2.2.
Tính nhanh:
H=2.2/1.5+2.2/5.9+2.2/9.13+......................+2.2/45.49
LƯU Ý: DẤU CHẤM LÀ NHÂN
\(H=\frac{2\cdot2}{1\cdot5}+\frac{2\cdot2}{5\cdot9}+...+\frac{2\cdot2}{45.49}\)
\(H=\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+...+\frac{4}{45\cdot49}\)
\(H=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{45}-\frac{1}{49}\)
\(H=1-\frac{1}{49}\)
\(H=\frac{48}{49}\)
\(H=\frac{2.2}{1.5}+\frac{2.2}{5.9}+\frac{2.2}{9.13}+...+\frac{2.2}{45.49}\)
\(\Rightarrow H=\frac{4}{1.5}+\frac{4}{5.9}+\frac{4}{9.13}+...+\frac{4}{45.49}\)
\(\Rightarrow H=\frac{5-1}{1.5}+\frac{9-5}{5.9}+...+\frac{49-45}{45.49}\)
\(\Rightarrow H=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{45}-\frac{1}{49}\)
\(\Rightarrow H=1-\frac{1}{49}=\frac{48}{49}\)
1/2+1/2.2+1/2.2.2+1/2.2.2.2+...+1/2.2.....2.2
\(A=\frac{1}{2.2^3}+\frac{1}{2.2^4}+\frac{1}{2.2^5}+....+\frac{1}{2.2^{100}}\)=?
2.2^2.2^3.2^4 ... 2^x = 2
2.2^2.2^3.2^4 ... 2^x = 2
(7x-11^3)=5^2.2^5+5^2.2^3
\((7x-11^3)=5^2\cdot2^5+5^2\cdot2^3\)
\(\Rightarrow(7x-11^3)=5^2\cdot(2^5+2^3)\)
\(\Rightarrow(7x-11^3)=25\cdot(32+8)\)
\(\Rightarrow(7x-11^3)=25\cdot40\)
\(\Rightarrow(7x-11^3)=1000\)
\(\Rightarrow7x=1000+11^3\)
\(\Rightarrow7x=1000+1331\)
\(\Rightarrow7x=2331\)
\(\Rightarrow x=333\)
2.2^2.2^3.2^4.....2^2016
2 . 22 . 23 . 24 . ... . 22016
= 21+2+3+4+...+2016
= 22033136
giải bài toán sau:
2.2+2.2+2-2.2
a.6
b.16
c.40
nhanh lên gấp lắm
2.2+2.2+2-2.2=6.
Vậy kết quả là A.6.
nha các bạn !