tìm x
17-(3+x)+15-|-3|=2+2x
tìm x
17/2 : x = 5
x-3/8 =2+1/4
`17/2 \div x=5`
`x=17/2 \div 5`
`x=17/10 = 1,7`
`----`
`x-3/8=2+1/4`
`x-3/8=9/4`
`x=9/4+3/8`
`x=21/8`
`\color{blue}\text {#DuyNam}`
\(\dfrac{17}{2}:x=5\)
\(x=\dfrac{17}{2}:5=\dfrac{17}{2}\times\dfrac{1}{5}\)
\(x=\dfrac{17}{10}\)
_____________________________
\(x-\dfrac{3}{8}=2+\dfrac{1}{4}\) \(=\dfrac{8}{4}+\dfrac{1}{4}\)
\(x-\dfrac{3}{8}=\dfrac{9}{4}\)
\(x=\dfrac{9}{4}+\dfrac{3}{8}=\dfrac{18}{8}+\dfrac{3}{8}\)
\(x=\dfrac{21}{8}\)
`17/2:x=5`
`x=17/2:5`
`x=17/10`
Vậy `x=17/10`
___________________
`x-3/8=2+1/4`
`x-3/8=9/4`
`x=9/4+3/8`
`x=21/8`
Vậy `x=21/8`
`@Nae`
tìm x
17/9 - x = 5/7 : 15/28
help meeeeeeeee
\(\dfrac{17}{9}-x=\dfrac{4}{3}\)
\(x=\dfrac{17}{9}-\dfrac{4}{3}\)
\(x=\dfrac{5}{9}\)
`17/9 - x = 5/7 : 15/28`
`=> 17/9 - x = 5/7 xx 28/15`
`=> 17/9 -x = 4/3`
`=> x = 17/9 - 4/3`
`=> x = 17/9 - 12/9`
`=> x = 15/9`
`=> x = 5/3`
Tính các tổng sau
2/11x13 + 2/13 x15 + 2/15 x17 + ............ + 2/95x97 +2/97x9 = ?
1 x 2 + 2 x 3 + 3 x 4 + 4 x 5 .......... + 99 x 100 = ?
Đặt A = 1.2 + 2.3 + 3.4 +.......... + 99.100
=> 3A = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ..... + 99.100.(101 - 98)
=> 3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + ....... + 99.100.101 - 98.99.100
=> 3A = (1.2.3 + 2.3.4 + 3.4.5 + ....... + 99.100.101) - (1.2.3 + 2.3.4 + ......... + 98.99.100)
=> 3A = 99.100.101
=> A = 99.100.101 : 3 = 999900
2/11x13+2/13x15+2/15x17+....+2/95x97+2/97x99
=1/11-1/13+1/13-1/15+1/15-1/17+....+1/95-1/97+1/97-1/99
=1/11-1/99
=9/99-1/99
=8/99
đúng nhé bạn
Đặt A = 1.2 + 2.3 + 3.4 +.......... + 99.100
=> 3A = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ..... + 99.100.(101 - 98)
=> 3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + ....... + 99.100.101 - 98.99.100
=> 3A = (1.2.3 + 2.3.4 + 3.4.5 + ....... + 99.100.101) - (1.2.3 + 2.3.4 + ......... + 98.99.100)
=> 3A = 99.100.101
=> A = 99.100.101 : 3 = 999900
Tìm x ϵ N biết :
a) 280 – ( x – 140 ) : 35 = 270 ;
b)( 190 – 2x ) : 35 – 32 = 16;
c) 720 : [ 41 – ( 2x – 5 ) ] = 23 .5
d) ( x : 23 + 45 ) . 37 – 22 = 24 . 105 ;
e) ( 3x – 4 ) . ( x – 1 ) 3 = 0 ;
f) 22x-1 : 4 = 83
g) x17 = x ;
h) ( x – 5 ) 4 = ( x – 5 ) 6 ;
i) ( x + 2 ) 5 = 210 ;
k ) 1 + 2 + 3 + … + x = 78
l) ( 3 .x – 24) . 73 = 2 .74 ;
n) 5x : 52 = 125 ;
m) ( x + 1) 2 = ( x + 1) 0 ;
o) ( 2 + x ) + ( 4 + x ) + ( 6 + x ) + ……+ ( 52 + x ) = 780 ;
p) 70⋮ x , 80 ⋮ x và x > 8
q) x ⋮ 12 , x ⋮ 25 , x ⋮ 30 và 0 < x < 500
TÌM X
( X cộng 5,42 ) x17 =142,29
X x 8 cộng X x 15 =653,2
( X + 5,42 ) x 17 = 142,29
X + 5,42 = 142,29 : 17
X + 5,42 = 8,37
X = 8,37 - 5,42
X = 2,95
X x 8 + X x 15 = 653,2
X x ( 8 + 15 ) = 653,2
X x 23 = 653,2
X = 653,2 : 23
x = 28,4
( x + 5,42 ) x 17 = 142,29 x . 8 + x . 15 = 653,2
x + 5,42 = 142,29 : 17 x . ( 8 + 15 ) = 653,2
x + 5,42 = 8,37 x . 23 = 653,2
x = 8,37 - 5,42 x = 653,2 : 23
x = 2,95 x = 28,4
x + 5,42 x 17 = 142,29
x + 5.42 =142,29 : 17
x + 5,42 = 8,37
x = 8,37 - 5,42
x = 2,95
X x 8 + X x 15 = 653,2
X x(8 + 15) = 653,2
X x 23 = 653,2
X = 653,2 : 23
X = 28,4
1 x 3 x 5 x 7 x 9 x 10 x 12 x 14 x 15 x17 x19 x20 = ?
ai nhanh mik tick cho ?
tìm x biết
a x^2 (2x+15)+4(2x+15)=0
b 5x(x-2)-3(x-2)=0
c 2(x+3)-x^2-3x=0
a
\(x^2\left(2x+15\right)+4\left(2x+15\right)=0\\ \Leftrightarrow\left(2x+15\right)\left(x^2+4\right)=0\\ \Leftrightarrow2x+15=0\left(x^2+4>0\forall x\right)\\ \Leftrightarrow2x=-15\\ \Leftrightarrow x=-\dfrac{15}{2}\)
b
\(5x\left(x-2\right)-3\left(x-2\right)=0\\ \Leftrightarrow\left(x-2\right)\left(5x-3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-2=0\\5x-3=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0+2=2\\x=\dfrac{0+3}{5}=\dfrac{3}{5}\end{matrix}\right.\)
c
\(2\left(x+3\right)-x^2-3x=0\\ \Leftrightarrow2\left(x+3\right)-\left(x^2+3x\right)=0\\ \Leftrightarrow2\left(x+3\right)-x\left(x+3\right)=0\\ \Leftrightarrow\left(x+3\right)\left(2-x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x+3=0\\2-x=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0-3=-3\\x=2-0=2\end{matrix}\right.\)
a: =>(2x+15)(x^2+4)=0
=>2x+15=0
=>2x=-15
=>x=-15/2
b; =>(x-2)(5x-3)=0
=>x=2 hoặc x=3/5
c: =>(x+3)(2-x)=0
=>x=2 hoặc x=-3
Tìm số tự nhiên x, biết
a, 2 x = 16
b, 3 x = 243
c, 5 x + 1 = 125
d, 5 x - 1 = 5
e, 4 2 x + 1 = 64
f, x 17 = x
a) x = 4
b) x = 5
c) x = 2
d) x = 2
e, x = 1
f, x = 0 hoặc x = 1
Tìm số tự nhiên x, biết
a) 2 x = 16
b) 3 x = 243
c) 5 x + 1 = 125
d) 5 x - 1 = 5
e) 4 2 x + 1 = 74
f) x 17 = x
a) x = 4
b) x = 5
c) x = 2
d) x = 2
e) x = 1
f) x = 0 hoặc x = 1.