Tìm x biết x.0,5=1.05-x
Tìm số tự nhiên x biết : (2/11.13+2/13.15+....+2/19.21).462-17/x+1.05= 19
Bài 8: Tính bằng cách thuận tiện a) 2,23 ×0,1 : 3,34 : 10 + × 4,43 b) 4,5 : 100 + 5,4 ×0,01 + × 0,1 Bài 9: Tìm x biết: x × 2,9 + x : 10 = 1.05
b: =(4,5+5,4)x0,01
=9,9x0,01
=0,099
tìm x
(2/11*13+2/13*15 + ... 2/19*21)*462 - [0.04/(x+1.05)] /0.12=19
`(2/(11.13)+2/(13.15)+....+2/(19.21)).462-[0,04/(x+1,05):0,12=19`
`=>(1/11-1/13+1/13-1/15+....+1/19-1/21).462-(2/(50(x+1,05)).25/3=19`
`=>(1/11-1/21).462-1/(3(x+1,05))=19`
`=>10/231. 462-1/(3x+3,15)=19`
`=>20-1/(3x+3,15)=19
`=>1/(3x+3,15)=1`
`=>3x+3,15=1`
`=>3x=-2,15`
`=>x=-43/60`
Vậy `x=-43/60`
Giải:
\(\left(\dfrac{2}{11.13}+\dfrac{2}{13.15}+...+\dfrac{2}{19.21}\right).462-\left[\dfrac{0,04}{x+1,05}:0,12\right]=19\)
\(\left(\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{15}+...+\dfrac{1}{19}-\dfrac{1}{21}\right).462-\left[\dfrac{1}{\dfrac{25}{x+\dfrac{21}{20}}}:\dfrac{3}{25}\right]=19\)
\(\left(\dfrac{1}{11}-\dfrac{1}{21}\right).462-\left[\dfrac{1}{25.\left(x+\dfrac{21}{20}\right)}:\dfrac{3}{25}\right]=19\)
\(20-\left[\dfrac{25.1}{3.25.\left(x+\dfrac{21}{20}\right)}\right]=19\)
\(\dfrac{1}{3.\left(x+\dfrac{21}{20}\right)}=20-19\)
\(\dfrac{1}{3.x+\dfrac{63}{20}}=1\)
\(1:\left(3.x+\dfrac{63}{20}\right)=1\)
\(3.x+\dfrac{63}{20}=1:1\)
\(3.x+\dfrac{63}{20}=1\)
\(3.x=1-\dfrac{63}{20}\)
\(3.x=\dfrac{-43}{20}\)
\(x=\dfrac{-43}{20}:3\)
\(x=\dfrac{-43}{60}\)
tìm X:
X x 3/4 + X/5 + 1.05 x X = 5.8
giúp mik nha mn ai đúng, ghi đầy đủ và nhanh mik cho tick.
a,tìm x: 60% x + 2/3x=-76
b,tìm x (2/11x13 +2 /13x15 +...+ 2/19x21 ).492 - [0,04 :(x+1.05)]:0,12=19
2/(11x13) = 1/11 - 1/13 ; 2/(13x15) = 1/13 - 1/15 ; 2/(15x17) = 1/15 - 1/17 ; 2/(17x19) = 1/17 - 1/19 ; 2/(19x21) = 1/19 - 1/21
2/(11x13) + 2/(13x15) + 2/(15x17) + 2/(17x19) 2/(19x21) =
1/11 - 1/13 + 1/13 - 1/15 + 1/15 - 1/17 + 1/17 - 1/19 + 1/19 - 1/21 = 1/11 - 1/21 = 101231
Hay: 10/231 x 462 - X = 19
20 - X = 19
X = 20 - 19
X = 1,đó là phần b
3/5x+2/3x=-76 <=> 19/15x=-76 <=> x=-60,đó là phần a
tìm s
s x 2,9 + s : 10 = 1.05
\(s\cdot2.9+s:10=s\cdot2.9+s\cdot0.1=s\cdot3=1,05\text{ nên }s=0,35\)
X x 2.9 + X :10 = 1.05
Tìm x biết : x * 3 + 45 - 0,5 * x = 90 - 0,5 * x
x * 3 + 45 - 0,5 * x = 90 - 0,5 * x
=> x * 3 +45 = 90 ( mỗi vế bớt x * 0,5)
=> x * 3 = 90 - 45
=> x * 3 = 45
=> x = 45 : 3 = 15
\(\left(\frac{2}{11.13}+\frac{2}{13.15}+..............\frac{2}{19.21}\right).462-\frac{17}{x+1.05}=19\)
Tìm x
\(\Leftrightarrow\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right).462-\frac{17}{x+1,05}=19.\)
\(\Leftrightarrow\left(\frac{1}{11}-\frac{1}{21}\right)462-\frac{17}{x+1,05}=19\)
\(\Leftrightarrow20-\frac{17}{x+1,05}=19\)
\(\Leftrightarrow1-\frac{17}{x+1,05}=0\)
\(\Leftrightarrow x+1,05=17\)
\(\Leftrightarrow x=15,95\)