Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
(y + \(\dfrac{1}{3}\)) + ( y + \(\dfrac{1}{9}\)) + ( y + \(\dfrac{1}{27}\)) + ( y + \(\dfrac{1}{81}\)) = \(\dfrac{56}{81}\)
( y + y + y + y ) + (\(\dfrac{1}{3}\)+ \(\dfrac{1}{9}\) + \(\dfrac{1}{27}\) + \(\dfrac{1}{81}\)) = \(\dfrac{56}{81}\)
4\(y\) + ( \(\dfrac{27}{81}\) + \(\dfrac{9}{81}\) + \(\dfrac{3}{27}\) + \(\dfrac{1}{81}\) ) = \(\dfrac{56}{81}\)
4y + \(\dfrac{40}{81}\) = \(\dfrac{56}{81}\)
4y = \(\dfrac{56}{81}\) - \(\dfrac{40}{81}\)
4y = \(\dfrac{16}{81}\)
y = \(\dfrac{16}{81}\) : 4
y = \(\dfrac{4}{81}\)
\(\left(y+\dfrac{1}{3}\right)+\left(y+\dfrac{1}{9}\right)+\left(y+\dfrac{1}{27}\right)+\left(y+\dfrac{1}{81}\right)=\dfrac{56}{81}\)
\(\Rightarrow y+\dfrac{1}{3}+y+\dfrac{1}{9}+y+\dfrac{1}{27}+y+\dfrac{1}{81}=\dfrac{56}{81}\)
\(\Rightarrow4\times y+\dfrac{40}{81}=\dfrac{56}{81}\)
\(\Rightarrow4\times y=\dfrac{56}{81}-\dfrac{40}{81}\)
\(\Rightarrow4\times y=\dfrac{16}{81}\)
\(\Rightarrow y=\dfrac{16}{81}:4\)
\(\Rightarrow y=\dfrac{4}{81}\)
a, (-72).(15 - 49) + 15.(-56 + 72)
= -72 . 15 + 72.49 - 15.56 + 15.72
= (-72.15 + 15.72) + (72.49 - 15.56)
= 3528 - 84
= 2688
1b, 1532 + (-186) + (-1432) + (-14) + 123
= (1532 - 1432) - (186 + 14) + 123
= 100 - 200 + 123
= 223 - 200
= 23
\(\left(y+\frac{1}{3}\right)+\left(y+\frac{1}{9}\right)+\left(y+\frac{1}{27}\right)+\left(y+\frac{1}{81}\right)=\frac{56}{81}\)
\(\Leftrightarrow4y+\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}\right)=\frac{56}{81}\)
\(\Leftrightarrow4y+\frac{40}{81}=\frac{56}{81}\)
\(\Leftrightarrow4y=\frac{56}{81}-\frac{40}{81}\)
\(\Leftrightarrow4y=\frac{16}{81}\)
\(\Rightarrow y=\frac{16}{81}\div4\)
\(\Rightarrow y=\frac{4}{81}\)
Vậy y có giá trị =\(\frac{4}{81}\)
< y 1/3 > < y 1/9> < y 1/27 > < y 1/81 > = 56 / 81
= 4y + < 1/3 + 1/9 + 1/27 + 1/81 > = 56 / 81
= 4y + 40 / 81 = 56 / 81
= 4y = 56 / 81 - 40 / 81
= 4 / 81