\(\frac{4}{5}x\frac{1}{4}+\frac{1}{2}x\frac{4}{5}\)
\(\frac{4}{5}x\left(\frac{1}{4}+\frac{1}{2}\right)\)
\(\frac{4}{5}x\frac{3}{4}=\frac{3}{5}\)
\(\frac{3}{4}x\frac{4}{5}+\frac{5}{6}x\frac{6}{7}x\frac{7}{8}\)
\(\frac{3}{5}+\frac{5}{8}=\frac{49}{40}\)
A) 4/5 x 1/4 + 1/2 x 4/5
= 4/5 x (1/4 + 1/2)
= 4/5 x (1/4 + 2/4)
= 4/5 x 3/4
= 3/5
OK
1. 1/2-(x-1/4)=1/3
=> x-1/4=1/2-1/3
=> x-1/4= 1/6
=> x= 1/6+1/4=5/12
2. 3/2*(x-1/2-1)=5/4
=> x-1/2-1=5/4:3/2
=> x-1/2= 5/6+1
=> x = 11/6+1/2
=> x= 7/3
3. 11/2-9/2*(x-3/4)=1
=> 9/2*(x-3/4)= 11/2-1
=> x-3/4 = 9/2:9/2
=> x= 1+3/4
=> x= 7/4
Chúc bạn Hk tốt!!!!!
1. x=\(\frac{5}{12}\)
2. x=\(\frac{7}{3}\)
3. x= \(\frac{7}{4}\)
Chúc bạn Hk tốt!!!
a) ( 1/2-1/3-1/6).(1/2+2/3+3/4+...+2017/2018) + 3/4.x = 9/10
0.(1/2+2/3+3/4+...+2017/2018) + 3/4.x = 9/10
0+3/4.x = 9/10
3/4.x = 9/10
x = 9/10: 3/4
x = 6/5
b) x + ( 3/1.3+3/3.5+...+3/13.15) = 11/5
x + 3/2. ( 1-1/3 + 1/3 - 1/5 + ...+ 1/13 - 1/15) = 11/5
x + 3/2. ( 1-1/15) = 11/5
x + 3/2.14/15 = 11/5
x + 7/5 = 11/5
x = 11/5 - 7/5
x = 4/5
\(a)\) \(S=1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+...+\frac{1}{2187}\)
\(S=1+\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^7}\)
\(3S=3+1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^6}\)
\(3S-S=\left(3+1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^6}\right)-\left(1+\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^7}\right)\)
\(2S=3+\frac{1}{3^7}\)
\(2S=\frac{3^8+1}{3^7}\)
\(S=\frac{3^8+1}{3^7}.\frac{1}{2}\)
\(S=\frac{3^8+1}{2.3^7}\)
Vậy \(S=\frac{3^8+1}{2.3^7}\)
Chúc bạn học tốt ~
a,
x+x×14÷27+x÷29=255�+�×14÷27+�÷29=255
⇒x+x×14×72+x×92=255⇒�+�×14×72+�×92=255
⇒x+x×78+x×92=255⇒�+�×78+�×92=255
⇒x.(1+78+92)=255⇒�.(1+78+92)=255
⇒x⋅
Đúng(0)
A=\(\dfrac{18360}{151}\)
B=\(\dfrac{1510}{3}\)
*Giải bằng casio
ghi phép tính đầy đủ ạ
a) \(x+x\times\dfrac{1}{4}:\dfrac{2}{7}+x\times\dfrac{2}{9}=255\)
\(x+x\times\dfrac{7}{8}+x\times\dfrac{2}{9}=255\)
\(x\times\left(1+\dfrac{7}{8}+\dfrac{2}{9}\right)=255\)
\(x\times\dfrac{151}{72}=255\)
\(x=255:\dfrac{151}{72}\)
\(x=\dfrac{18360}{151}\)
Em viết lại đề cho chuẩn hơn đi chỗ x2/9
b) \(\dfrac{2}{3}+\dfrac{1}{3}\times x+\dfrac{11}{3}\times x=2014\)
\(\dfrac{1}{3}\times x+\dfrac{11}{3}\times x=2014-\dfrac{2}{3}\)
\(x\times\left(\dfrac{1}{3}+\dfrac{11}{3}\right)=\dfrac{6040}{3}\)
\(x\times4=\dfrac{6040}{3}\)
\(x=\dfrac{6040}{3}:4\)
\(x=\dfrac{1510}{3}\)