tính
20^5 . 5^10 / 100^5
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`687 + (2 × 5) + 10`
`= 687 + 10 + 10`
`= 697 + 10`
`= 707`
\(\frac{5}{4.7}+\frac{5}{7.10}+\frac{5}{10.13}+...+\frac{5}{97.100}\)
\(=5\left(\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+...+\frac{1}{97.100}\right)\)
\(=5.\frac{1}{3}\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{97}-\frac{1}{100}\right)\)
\(=\frac{5}{3}\left(\frac{1}{4}-\frac{1}{100}\right)\)
\(=\frac{2}{5}\)
tìm x:
a
x - 10 + 5 = 100
x - 10 =100-5=95
x=95+10=105
b
x + 10 - 5 = 100
x + 10 = 100 + 5 = 105
x = 105 - 10 = 95
tích mik ủng hộ nha bà con cô bác ơi
`Answer:`
\dfrac15+\dfrac1{5+10}+\dfrac1{5+10+15}\ +\,.\!.\!.+\ \dfrac1{5+10+15\ +\,.\!.\!.+\ 100}\\=\dfrac15+\dfrac1{5.(1+2)}+\dfrac1{5.(1+2+3)}\ +\,.\!.\!.+\ \dfrac1{5.(1+2+3\ +\,.\!.\!.+\ 20)}\\=\dfrac15\left(1+\dfrac1{1+2}+\dfrac1{1+2+3}\ +\,.\!.\!.+\ \dfrac1{1+2+3\ +\,.\!.\!.+\ 20}\right)\\=\dfrac15\bigg(\dfrac22+\dfrac26+\dfrac2{12}\ +\,.\!.\!.+\ \dfrac2{20.21}\bigg)\\=\dfrac25\left(\dfrac1{1.2}+\dfrac1{2.3}+\dfrac1{3.4}\ +\,.\!.\!.+\ \dfrac1{20.21}\right)\\=\dfrac25\left(1-\dfrac12+\dfrac12-\dfrac13+\dfrac13-\dfrac14\ +\,.\!.\!.+\ \dfrac1{20}-\dfrac1{21}\right)\\=\dfrac25\left(1-\dfrac1{21}\right)\\=\dfrac25\!\cdot\!\dfrac{20}{21}\\=\dfrac8{21}
`Answer:`
Mình gửi lại bài nhé. Mong lần này không bị lỗi như lần trước.
\(\dfrac15+\dfrac1{5+10}+\dfrac1{5+10+15}\ +\,.\!.\!.+\ \dfrac1{5+10+15\ +\,.\!.\!.+\ 100}\\=\dfrac15+\dfrac1{5.(1+2)}+\dfrac1{5.(1+2+3)}\ +\,.\!.\!.+\ \dfrac1{5.(1+2+3\ +\,.\!.\!.+\ 20)}\\=\dfrac15\left(1+\dfrac1{1+2}+\dfrac1{1+2+3}\ +\,.\!.\!.+\ \dfrac1{1+2+3\ +\,.\!.\!.+\ 20}\right)\\=\dfrac15\bigg(\dfrac22+\dfrac26+\dfrac2{12}\ +\,.\!.\!.+\ \dfrac2{20.21}\bigg)\\=\dfrac25\left(\dfrac1{1.2}+\dfrac1{2.3}+\dfrac1{3.4}\ +\,.\!.\!.+\ \dfrac1{20.21}\right)\\=\dfrac25\left(1-\dfrac12+\dfrac12-\dfrac13+\dfrac13-\dfrac14\ +\,.\!.\!.+\ \dfrac1{20}-\dfrac1{21}\right)\\=\dfrac25\left(1-\dfrac1{21}\right)\\=\dfrac25\!\cdot\!\dfrac{20}{21}\\=\dfrac8{21}\)
Chữ số 5 trong số thập phân 62,359 có giá trị là bao nhiêu?
A.5
B. 5/10
C.5/100
D.5/100
\(\frac{20^5.5^{10}}{100^5}\)
\(=\frac{20^5.5^5.5^5}{100^5}\)
\(=\frac{100^5.5^5}{100^5}\)
\(=5^5\)
\(=3125\)
Học tốt !!! ~
\(\frac{20^5\cdot5^{10}}{100^5}=\frac{4^5\cdot5^5\cdot5^{10}}{4^5\cdot25^5}=\frac{4^5\cdot5^5\cdot25^5}{4^5\cdot25^5}=5^5=3125\)