a)( 13/12 + 4/3) : 2/3= ; b) 5/6 - 3/8) x 2 và 1/2
Tính giá trị của các biểu thức sau một cách hợp lý:
a)A=\(\frac{3^{10}.11+3^{10}.5}{3^9.2^4+2^{10}.13}+\frac{2^{10}.13+2^{10}.65}{2^8.104}\)
b)B=\(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)
a. ( 19 5/8 : 7/12 - 13 1/4 : 7/12) . 4/5
b.( - 2/5 + 3/7) - (4/9 + 12/20 - 13/35) + 7/35
c. ( 4 5/57 - 3/ 4/51 + 8 13/29) - ( 3 5/57 - 6 16/29)
\(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)
\(=\left(\frac{157}{8}:\frac{7}{12}-\frac{53}{4}:\frac{7}{12}\right).\frac{4}{5}\)
\(=\left[\left(\frac{157}{8}-\frac{53}{4}\right):\frac{7}{12}\right].\frac{4}{5}\)
\(=\left[\frac{51}{8}:\frac{7}{12}\right].\frac{4}{5}\)
\(=\frac{153}{14}.\frac{4}{5}\)
\(=\frac{306}{35}\)
\(\left(\frac{-2}{5}+\frac{3}{7}\right)-\left(\frac{4}{9}+\frac{12}{20}-\frac{13}{35}\right)+\frac{7}{35}\)
\(=\frac{1}{35}-\frac{212}{315}+\frac{7}{35}\)
\(=\frac{1}{35}+\frac{-212}{315}+\frac{7}{35}\)
\(=\frac{9}{315}+\frac{-212}{315}+\frac{63}{315}\)
\(=\frac{-140}{315}=\frac{-4}{9}\)
\(\left(4\frac{5}{57}-3\frac{4}{51}+8\frac{13}{29}\right)-\left(3\frac{5}{57}-6\frac{16}{29}\right)\)
\(=\left(\frac{233}{57}-\frac{157}{51}+\frac{245}{29}\right)-\left(\frac{176}{57}-\frac{190}{29}\right)\)
\(=\frac{1941}{323}-\frac{-5726}{1653}\)
\(=\frac{14011}{1479}\)
a) \(4^{13}+4^{14}+4^{15}+4^{16}=4^{13}\left(1+4\right)+4^{14}\left(1+4\right)=4^{13}.5+4^{14}.5=5\left(4^{13}+4^{14}\right)⋮5\Rightarrow dpcm\)
c) \(2^{10}+2^{11}+2^{12}+2^{13}+2^{14}+2^{15}\)
\(=2^{10}\left(1+2+2^2\right)+2^{13}\left(1+2+2^2\right)\)
\(=2^{10}.7+2^{13}.7=7\left(2^{10}+2^{13}\right)⋮7\Rightarrow dpcm\)
Câu c bạn xem lại đê
Bài 4: Tính nhanh:
a, A =\(\left(\frac{84}{13}\right)^2+\left(\frac{35}{13}\right)^2\)
b, B = \(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}\div\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)
c, C =\(\frac{1\times2+2\times4+3\times6+4\times8+5\times10}{3\times4+6\times8+9\times12+12\times16+15\times20}\)
A = 7/12 + 5/12 : 6 - 11/36
B= ( 4/5 + 1/2 ) : ( 3/13 - 8/13 )
C = ( 2/3 - 1/4 + 5/11) : ( 5/12 + 1 - 7/11 )
A) 7/12+5/12 : 6 -11/36
=7/12 + 5/72 -11/36
=47/72-11/36
=25/72
Bài 1
a) 12/17 + 21/25 =
b) 4 - 205/811 =
c) 12 * 21/25 =
d) 4 : 205/811 =
Bài 2 : Tính
a) 3 11/12 + 12 7/24 =
b)13 3/14 - 5 13/28 =
c) 3 11/12 * 12 7/24=
d) 13 3/14 : 5 13/28 =
Bài 3 : Tính
a) 32/35 - 7/20 + 4/5 =
b)2 3/7 + 4 15/24 - 3 12/19 =
Bài 4 : Viết số tự nhiên thích hợp vào chỗ trống ;
a) 2 3/13 < ...< 3 1/2
b) 12 3/13<...*3< 16 1/2
a) 12/17 + 21/25 = 657/425
b) 4 - 205/811 = 3039/811
c) 12 . 21/25 = 252/25
d) 4 : 205/811 = 205/3244
a) 12/17 + 21/25 = 657/425
b) 4 - 205/811 = 3039/811
c) 12 . 21/25 = 252/25
d) 4 : 205/811 = 205/3244
tinh giá trị biểu thức A=[(2^22*13+13+2*12*65)/(2^10*10^4)]+[(3^10*11+3^10*5)/(3^)9*2*4)]
Tính
a, -6/11: ( 3/5 . 4/11)
b, 7/12+5/12:6-14/30
c, ( 4/5 + 1/2 ): ( 3/13-8/13)
d, ( 2/3 -1/4 +5/11):(5/12+1-7/11)
a)\(\dfrac{-6}{11}:\left(\dfrac{3}{5}.\dfrac{4}{11}\right)=\dfrac{-5}{2}\)
b)\(\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{14}{30}=\dfrac{67}{370}\)
c)\(\left(\dfrac{4}{5}+\dfrac{1}{2}\right):\left(\dfrac{3}{13}-\dfrac{8}{13}\right)=-\dfrac{169}{50}\)
d)\(\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right):\left(\dfrac{5}{12}+1-\dfrac{7}{11}\right)=\dfrac{115}{103}\)
a) x/8 = 3/4 + -5/8
b) x/12 = 3/4 + -2/3
c) 1 + 11/13 = 24/x
d) x/6 - 3/4 = 1/12
`x/8 = 3/4 +(-5/8)`
`=>x/8 = 6/8 +(-5/8)`
`=>x/8 = 1/8`
`=>x=1`
`-----`
`x/12 =3/4 +(-2/3)`
`=>x/12 = 9/12 + (-8/12)`
`=> x/12=1/12`
`=>x=1`
`----`
`1+11/13=24/x`
`=> 13/13 +11/13=24/x`
`=> 24/13 =24/x`
`=>x=13`
`----`
`x/6 -3/4=1/12`
`=>x/6 = 1/12 +3/4`
`=>x/6 = 1/12 + 9/12`
`=>x/6 = 10/12`
`=>x/6= 5/6`
`=>x=5`
\(a)\)
\(\dfrac{x}{8}=\dfrac{3}{4}+\dfrac{-5}{8}\)
\(\Rightarrow\dfrac{x}{8}=\dfrac{1}{8}\)
\(\Rightarrow x.8=1.8\)
\(\Rightarrow x.8=8\)
\(\Rightarrow x=8:8\)
\(\Rightarrow x=1\)
\(b)\)
\(\dfrac{x}{12}=\dfrac{3}{4}+\dfrac{-2}{3}\)
\(\Rightarrow\dfrac{x}{12}=\dfrac{1}{12}\)
\(\Rightarrow x.12=1.12\)
\(\Rightarrow x.12=12\)
\(\Rightarrow x=12:12\)
\(\Rightarrow x=1\)
\(c)\)
\(1+\dfrac{11}{13}=\dfrac{24}{x}\)
\(\Rightarrow\dfrac{24}{13}=\dfrac{24}{x}\)
\(\Rightarrow x.24=24.13\)
\(\Rightarrow x.24=312\)
\(\Rightarrow x=312:24\)
\(\Rightarrow x=13\)
\(d)\)
\(\dfrac{x}{6}-\dfrac{3}{4}=\dfrac{1}{12}\)
\(\Rightarrow\dfrac{x}{6}=\dfrac{1}{12}+\dfrac{3}{4}\)
\(\Rightarrow\dfrac{x}{6}=\dfrac{5}{6}\)
\(\Rightarrow x.6=5.6\)
\(\Rightarrow x.6=30\)
\(\Rightarrow x=30:6\)
\(\Rightarrow x=5\)
Tinh gia tri bieu thuc:
A,3/1.6+3/6.11+...+3/96.101. B,1+1/2+1/2^2+1/2^3+....+1/2^2006. C,-1/3+1/3^2+1/3^3+...+1/3^100-1/3^101. D,12-12/7-12/289-12/85 phần 4-4/7-4/289-4/85:3+3/13+3/169+3/91 phần 7+7/13+7/169+7/91