Thu gọn :
S = \(\dfrac{2}{3^2}+\dfrac{2}{3^4}+\dfrac{2}{3^6}+...+\dfrac{2}{3^{50}}\)
Thu gọn :
C = \(\dfrac{\dfrac{1}{2}-\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{3}{4}}{\dfrac{2}{3}-\dfrac{2}{3}:\dfrac{5}{6}-\dfrac{5}{6}}\)
Biết nhưng ko giúp đâu, bài dễ thì phải động não nha
Bài này có lẽ không làm được bn ạ, vì ở dưới mẫu có 2 số hạng \(\dfrac{2}{3}\)
chia cho 0 rùi, mà không có số nào chia được cho 0 cả, lặp luôn cả cái này ở tử nữa!!!
Thu gọn:
A = \(\dfrac{2^4.3^3+2^3.3^4}{2^5.3^3-2^4.3^2}\) D = \(\dfrac{\left(\dfrac{1}{2}-\dfrac{1}{3}\right).\left(\dfrac{2}{3}-\dfrac{3}{4}\right)}{\left(\dfrac{1}{2}+\dfrac{1}{3}\right).\left(\dfrac{2}{3}+\dfrac{3}{4}\right)}\)
B = \(\dfrac{2^3-3^4-2^4.3^3}{2^5.3^4-2^6.3^3}\) E = \(\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{3}{4}\right).\left(\dfrac{2}{3}-\dfrac{3}{4}+\dfrac{5}{6}\right)\)
C = \(\dfrac{\dfrac{1}{2}-\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{3}{4}}{\dfrac{2}{3}-\dfrac{2}{3}:\dfrac{5}{6}-\dfrac{5}{6}}\)
Giúp mình với ! 10k nha
\(A=\dfrac{2^4.3^3+2^3.3^4}{2^5.3^4-2^6.3^3}=\dfrac{2^3.3^3.\left(2+3\right)}{2^5.3^3.\left(3-2\right)}=\dfrac{2^3.3^3.5}{2^5.3^3.1}\)
\(=\dfrac{5}{2^2}=\dfrac{5}{4}\)
o) \(\dfrac{\left(-1\right)^6.3^5.4^3}{9^2.2^5}\)
s) \(\dfrac{\dfrac{2}{7}+\dfrac{2}{5}+\dfrac{2}{17}-\dfrac{2}{25}}{\dfrac{3}{14}+\dfrac{3}{10}+\dfrac{3}{34}-\dfrac{3}{50}}\)
t) \(\sqrt{\dfrac{4}{9}}\) - \(\dfrac{1}{2}\): \(\left|\dfrac{-2}{3}\right|\)
Mg giải gấp giúp mình với
o: \(\dfrac{\left(-1\right)^6\cdot3^5\cdot4^3}{9^2\cdot2^5}=\dfrac{3^5\cdot2^6}{2^5\cdot3^4}=\dfrac{3^5}{3^4}\cdot\dfrac{2^6}{2^5}=3\cdot2=6\)
s: \(\dfrac{\dfrac{2}{7}+\dfrac{2}{5}+\dfrac{2}{17}-\dfrac{2}{25}}{\dfrac{3}{14}+\dfrac{3}{10}+\dfrac{3}{34}-\dfrac{3}{50}}\)
\(=\dfrac{2\left(\dfrac{1}{7}+\dfrac{1}{5}+\dfrac{1}{17}-\dfrac{1}{25}\right)}{\dfrac{3}{2}\left(\dfrac{1}{7}+\dfrac{1}{5}+\dfrac{1}{17}-\dfrac{1}{25}\right)}\)
\(=2:\dfrac{3}{2}=\dfrac{4}{3}\)
t: \(\sqrt{\dfrac{4}{9}}-\dfrac{1}{2}:\left|-\dfrac{2}{3}\right|\)
\(=\dfrac{2}{3}-\dfrac{1}{2}:\dfrac{2}{3}\)
\(=\dfrac{2}{3}-\dfrac{3}{4}=\dfrac{8-9}{12}=-\dfrac{1}{12}\)
So sánh:
a, \(\dfrac{1}{3}+\dfrac{1}{3^2}+...+\dfrac{1}{3^{50}}\) và \(\dfrac{1}{2}\)
b, \(\dfrac{1}{4}-\dfrac{1}{4^2}+\dfrac{1}{4^3}-...+\dfrac{1}{4^{99}}\) và \(\dfrac{1}{12}\)
c, \(\dfrac{1}{3}+\dfrac{2}{3^2}+\dfrac{3}{3^3}+...+\dfrac{50}{3^{50}}\) và \(\dfrac{3}{4}\)
a/ Đặt :
\(A=\dfrac{1}{3}+\dfrac{1}{3^2}+.........+\dfrac{1}{3^{50}}\)
\(\Leftrightarrow3A=1+\dfrac{1}{3}+\dfrac{1}{3^2}+.......+\dfrac{1}{3^{49}}\)
\(\Leftrightarrow3A-A=\left(1+\dfrac{1}{3}+....+\dfrac{1}{3^{49}}\right)-\left(\dfrac{1}{3}+\dfrac{1}{3^2}+....+\dfrac{1}{3^{50}}\right)\)
\(\Leftrightarrow2A=1-\dfrac{1}{3^{50}}\)
còn sao nx thì mk chịu =.=
* Rút gọn biểu thức
c.\(\dfrac{1}{2\sqrt{2}}-\dfrac{3}{2}\sqrt{4,5}+\dfrac{2}{5}\sqrt{50}\)
d.\(\dfrac{4}{3+\sqrt{5}}-\dfrac{8}{1+\sqrt{5}}+\dfrac{15}{\sqrt{5}}\)
`c)1/(2sqrt2)-3/2sqrt{4,5}+2/5sqrt{50}`
`=1/(2sqrt2)-3/2sqrt{9/2}+2/5sqrt{25.2}`
`=1/(2sqrt2)-9/(2sqrt2)+2sqrt2`
`=2sqrt2-8/(2sqrt2)`
`=2sqrt2-sqrt2=sqrt2`
`d)4/(3+sqrt5)-8/(1+sqrt5)+15/sqrt5`
`=(4(3-sqrt5))/(9-5)-(8(sqrt5-1))/(5-1)+3sqrt5`
`=3-sqrt5-2(sqrt5-1)+3sqrt5`
`=3+3sqrt5-3sqrt5+2=5`
Bài 1: Thu gọn đơn thức ( a là hằng só )
a) \(1\dfrac{1}{4}x^2y\left(\dfrac{-5}{6}xy\right)^0.\left(-2\dfrac{1}{3}xy\right)\)
b) \(\dfrac{1}{2}x.\dfrac{1}{4}x^2.\dfrac{x^3}{8}.2y.4y^2.x^3\)
c) \(\left(\dfrac{-9}{2}\right)^3.3xy\left(4a^2x^3\right)\left(4\dfrac{1}{3}ay^2\right)\)
d) \(\left(\dfrac{1}{3}xy^2\right)^3\left(\dfrac{-3}{7}x^4y\right)^2\)
Thu gọn P
\(P=\dfrac{x-\sqrt{x}}{x-9}+\dfrac{1}{\sqrt{x}+3}-\dfrac{1}{\sqrt{x}-3}\)
a) Tính P biết \(x=\sqrt{6+4\sqrt{2}}+\sqrt{6-4\sqrt{2}}\)
b) Tính P biết \(x=\dfrac{1}{\sqrt{2}-1}-\dfrac{1}{\sqrt{2}+1}\)
Thu gọn các đơn thức sau,xác định hệ số và tìm bậc
a) \(\dfrac{1}{2}\)( \(^{x^3}\)).(\(\dfrac{-3}{4}\))\(^{x^2}\)
b) (-2x)\(^{^2}\).(\(\dfrac{1}{2}\))\(^{^3}\)
c) (\(\dfrac{4}{5}\)x)\(^{^2}\).\(\dfrac{15}{2}\).\(^{x^3}\)
d) \(\dfrac{2}{9}^{x^2}\).(\(\dfrac{3}{2}\))\(^{^2}\)
e) (\(\dfrac{3}{5}\)x)\(^{^2}\).(\(\dfrac{5
}{2}\)\(^{x^3}\))\(^{^2}\)
GIÚP MIK VỚI MIK ĐANG CẦN GẤP GẤP!!!THANKS MỌI NGƯỜI
a: \(=\dfrac{-3}{8}x^5\)
Hệ số là -3/8
Bậc là 5
b: \(=4x^2\cdot\dfrac{1}{8}=\dfrac{1}{2}\cdot x^2\)
Hệ sốlà 1/2
Bậc là 2
c: \(=\dfrac{16}{25}x^2\cdot\dfrac{15}{2}x^3=\dfrac{24}{5}x^5\)
Hệ số là 24/5
Bậc là 5
d: \(=\dfrac{2}{9}\cdot\dfrac{9}{4}\cdot x^2=\dfrac{1}{2}x^2\)
Hệ số là 1/2
Bậc là 2
e: \(=\dfrac{9}{25}x^2\cdot\dfrac{25}{4}x^6=\dfrac{9}{4}x^8\)
Hệ số là 9/4
Bậc là 8
Tìm x biết:
\(a,\left(x-\dfrac{3}{4}\right)+50\%=\dfrac{1}{6}\)
\(b,\dfrac{1}{2}x-\dfrac{5}{6}x=\dfrac{7}{2}\)
\(c,\left(4-x\right)\left(3x+5\right)=0\)
\(d,\dfrac{x}{16}=\dfrac{50}{32}\)
\(e,\left(2x-3\right)+\dfrac{3}{2}=-\dfrac{1}{4}\)
a: =>x-3/4=1/6-1/2=1/6-3/6=-2/6=-1/3
=>x=-1/3+3/4=-4/12+9/12=5/12
b: =>x(1/2-5/6)=7/2
=>-1/3x=7/2
hay x=-21/2
c: (4-x)(3x+5)=0
=>4-x=0 hoặc 3x+5=0
=>x=4 hoặc x=-5/3
d: x/16=50/32
=>x/16=25/16
hay x=25
e: =>2x-3=-1/4-3/2=-1/4-6/4=-7/4
=>2x=-7/4+3=5/4
hay x=5/8