tìm x
17-(3+x)+15-|-3|=2+2x
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`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}`
\(\dfrac{17}{2}:x=5\)
\(x=\dfrac{17}{2}:5=\dfrac{17}{2}\times\dfrac{1}{5}\)
\(x=\dfrac{17}{10}\)
_____________________________
\(x-\dfrac{3}{8}=2+\dfrac{1}{4}\) \(=\dfrac{8}{4}+\dfrac{1}{4}\)
\(x-\dfrac{3}{8}=\dfrac{9}{4}\)
\(x=\dfrac{9}{4}+\dfrac{3}{8}=\dfrac{18}{8}+\dfrac{3}{8}\)
\(x=\dfrac{21}{8}\)
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
( 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
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
a) x = 4
b) x = 5
c) x = 2
d) x = 2
e, x = 1
f, x = 0 hoặc x = 1
a) x = 4
b) x = 5
c) x = 2
d) x = 2
e) x = 1
f) x = 0 hoặc x = 1.
17-(3+x)+15-|-3|=2+2x
17-3-x+15-3=2+2x
26-x=2+2x
-x-2x=2-26
-3x=-24
x=8
Ta có: \(17-\left(3+x\right)+15-\left|-3\right|=2+2x\)
\(\Leftrightarrow17-3-x+15-3-2-2x=0\)
\(\Leftrightarrow-3x+24=0\)
\(\Leftrightarrow-3x=-24\)
hay x=8