3 + 6/11
a ) 4 . 3^x-1 + 2 . 3^x+2 = 4 . 3^6 + 2 . 3^9
b ) 5^x+4 - 3 . 5^x+3 = 2 . 5^11
c ) 11 . 6^x-1 = 11 . 6^11 + 2 . 6^13
\(4.3^{x-1}+2.3^{x+2}=4.3^6+2.3^9\)
\(3^{x-1}.\left(4+2.3^3\right)=3^6.\left(4+2.3^3\right)\)
\(\Leftrightarrow3^{x-1}=3^6\)
\(\Leftrightarrow x-1=6\)
\(\Leftrightarrow x=7\)
Vậy \(x=7\)
\(5^{x+4}-3.5^{x+3}=2.5^{11}\)
\(\Leftrightarrow5^{x+3}.\left(5-3\right)=2.5^{11}\)
\(\Leftrightarrow5^{x+3}.2=2.5^{11}\)
\(\Leftrightarrow5^{x+3}=5^{11}\)
⇔\(x+3=11\)
\(\Leftrightarrow x=8\)
Vậy \(x=8\)
\(11.6^{x-1}=11.6^{11}+2.6^{13}\)
\(\Rightarrow11.6^{x-1}=6^{11}.\left(11+2.36\right)\)
\(\Rightarrow11.6^{x-1}=6^{11}.83\)
Giá trị của biểu thức 11/15 : 11/6 + 11/6 : 11/15 là:A. 1B. 29/10C. 3/11D. 11/3
3/1*6+3/6*11+3/11*16+...+3/96*101
Ta có : 3/ 1 x 6 + 3/6 x 11 + 3/11 x 16 + ...+ 3/96 x 101
= 3/5 x ( 5/1 x 6 + 5/6 x 11 + 5/11 x 16 + ...+ 5/96 x 101 )
= 3/5 x ( 1 - 1/6 + 1/6 - 1/11 + 1/11 - 1/16 + ...+ 1/96 - 1/101 )
= 3/5 x ( 1 - 1/101 )
= 3/5 x 100/101
= 60/101
Tham khảo nha !!!
3/1*6 + 3/6*11 + 3/11*16 +...+ 3/61*66
Đặt A = \(\dfrac{3}{1.6}+\dfrac{3}{6.11}+...+\dfrac{3}{61.66}\)
=> \(\dfrac{5}{3}A=\dfrac{5}{1.6}+\dfrac{5}{6.11}+...+\dfrac{5}{61.66}\)
=> \(\dfrac{5}{3}A=1-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{11}+...+\dfrac{1}{61}-\dfrac{1}{66}\)
=> \(\dfrac{5}{3}A=1-\dfrac{1}{66}=\dfrac{65}{66}\)
=> A = \(\dfrac{13}{22}\)
@nam nguyen
Đặt :
\(Â=\dfrac{3}{1.6}+\dfrac{3}{6.11}+...............+\dfrac{3}{61.66}\)
\(\Leftrightarrow A.\dfrac{5}{3}=\dfrac{5}{1.6}+\dfrac{5}{6.11}+..............+\dfrac{5}{61.66}\)
\(\Leftrightarrow A\dfrac{5}{3}=1-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{11}+.........+\dfrac{1}{61}-\dfrac{1}{66}\)
\(\Leftrightarrow A.\dfrac{5}{3}=1-\dfrac{1}{66}\)
\(\Leftrightarrow A.\dfrac{5}{3}=\dfrac{65}{66}\)
\(\Leftrightarrow A=\dfrac{13}{22}\)
Đặt \(A=\dfrac{3}{1.6}+\dfrac{3}{6.11}+\dfrac{3}{11.16}+...+\dfrac{3}{61.66}\)
\(A=3.\dfrac{1}{5}.\left(\dfrac{5}{1.6}+\dfrac{5}{6.11}+\dfrac{5}{11.16}+...+\dfrac{5}{61.66}\right)\)
\(A=\dfrac{3}{5}.\left(1-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}+...+\dfrac{1}{61}-\dfrac{1}{66}\right)\)
\(A=\dfrac{3}{5}.\left(1-\dfrac{1}{66}\right)\)
\(A=\dfrac{3}{5}.\dfrac{65}{66}=\dfrac{13}{22}\)
3/5+3/7-3/11
_____________
6/5+6/7-6/11
rut 2 ra khoi mau so ,ben trong la 3/5+3/7+3/11
kết quả là 1/2
\(\frac{\frac{3}{5}+\frac{3}{7}-\frac{3}{11}}{\frac{6}{5}+\frac{6}{7}-\frac{6}{11}}=\frac{3.\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}\right)}{6.\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}\right)}\)\(=\frac{1}{2}\).
11 3/4 - ( 6 5/6 - 4 1/2 ) + 1 2/3
( vd 11 3/4 có nghĩa là 11 và 3/4 nhé ! )
Giải:
\(11\dfrac{3}{4}-\left(6\dfrac{5}{6}-4\dfrac{1}{2}\right)+1\dfrac{2}{3}\)
\(=\dfrac{47}{4}-\left(\dfrac{41}{6}-\dfrac{9}{2}\right)+\dfrac{5}{3}\)
\(=\dfrac{47}{4}-\dfrac{41}{6}+\dfrac{9}{2}+\dfrac{5}{3}\)
\(=\dfrac{141}{12}-\dfrac{82}{12}+\dfrac{54}{12}+\dfrac{20}{12}\)
\(=\dfrac{141-82+54+20}{12}\)
\(=\dfrac{133}{12}\)
Chúc bạn học tốt!
Tính:
a, -3/4 + -5/4 + -7/4
b, -6/11 + 5/-11 + -2/11 + 6/11
a: \(=\dfrac{-3-5-7}{4}=\dfrac{-15}{4}\)
b: \(=\dfrac{-6-5-2+6}{11}=\dfrac{-7}{11}\)
Giải ô chữ dưới đây.
Biết rằng.
L. \(\dfrac{7}{6}+\dfrac{8}{6}\) T. \(\dfrac{1}{11}+\dfrac{7}{11}+\dfrac{9}{11}\)
Ạ. \(\dfrac{4}{11}+\dfrac{2}{11}\) Đ. \(\dfrac{3}{6}+\dfrac{1}{6}+\dfrac{7}{6}\) À. \(\dfrac{3}{11}+\dfrac{9}{11}\)
L: \(\dfrac{7}{6}\) +\(\dfrac{8}{6}\) = \(\dfrac{15}{6}\)
T: \(\dfrac{1}{11}\) + \(\dfrac{7}{11}\) + \(\dfrac{9}{11}\) = \(\dfrac{17}{11}\)
Ạ: \(\dfrac{4}{11}\) + \(\dfrac{2}{11}\) = \(\dfrac{6}{11}\)
Đ: \(\dfrac{3}{6}\) + \(\dfrac{1}{6}\) + \(\dfrac{7}{6}\) = \(\dfrac{11}{6}\)
À: \(\dfrac{3}{11}\) + \(\dfrac{9}{11}\) = \(\dfrac{12}{11}\)
Tính giá trị các biểu thức sau một cách hợp lí:
A = 5/11 . 5/7 + 5/11 . 2/7 + 6/11
B= 3/13 . 6/11 + 3/13 . 9/11 – 3/13 . 4/11
C= ( 12/16 – 31/22 + 14/91 ) . (1/2 – 1/3 – 1/6 )
Hãy giúp mk
\(A=\dfrac{5}{11}.\dfrac{5}{7}+\dfrac{5}{11}.\dfrac{2}{7}+\dfrac{6}{11}=\dfrac{5}{11}\left(\dfrac{5}{7}+\dfrac{2}{7}\right)+\dfrac{6}{11}=\dfrac{5}{11}.1+\dfrac{6}{11}=\dfrac{5}{11}+\dfrac{6}{11}=\dfrac{11}{11}=1\)
\(B=\dfrac{3}{13}.\dfrac{6}{11}+\dfrac{3}{13}.\dfrac{9}{11}-\dfrac{3}{13}.\dfrac{4}{11}=\dfrac{3}{13}\left(\dfrac{6}{11}+\dfrac{9}{11}-\dfrac{4}{11}\right)=\dfrac{3}{13}.1=\dfrac{3}{13}\)
\(C=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{3}{6}-\dfrac{2}{6}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right).0=0\)
Điền dấu >, <, =
6 + 8 ….. 8 + 6
6 + 6 ….. 6 + 8
9 + 8 – 5 ….. 11
6 + 7 – 3 ….. 11
Phương pháp giải:
- Tính giá trị của mỗi vế.
- So sánh rồi điền dấu thích hợp vào chỗ trống.
Lời giải chi tiết:
6 + 8 = 8 + 6
6 + 6 < 6 + 8
9 + 8 – 5 > 11
6 + 7 – 3 < 11