18:4*3+34-23
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\(\dfrac{11}{34}+\dfrac{5}{23}+\dfrac{23}{34}+\dfrac{18}{23}\)
\(=\left(\dfrac{11}{34}+\dfrac{23}{34}\right)+\left(\dfrac{5}{23}+\dfrac{18}{23}\right)\)
\(=1+1\)
\(=2\)
#DatNe
(x+3).(2x-18)=0
=>x+3=0 hoặc 2x-18 =0
+)x+3=0
x=-3
+)2x-18=0
2x =18
x =9
Vậy x \(\in\)\(_{\left\{-3;9\right\}}\)
=-(23.3.4.7)=-1932
=2.8.14.3=672
=-(34+26+91+99)=-250
=82+(-120)=-(120-82)=-38
=20.(-4)+31.(-20)=20.(-4-31)=20.(-35)=-700
=125+/-25/=125+25=150
=26+34=60
=(-275) +115=-160
=(-34)+34=0
=-18.31-28.(-24)=-555+672=114
\(a.2x+35=x-27\)
\(\Leftrightarrow2x-x=-27-35\)
\(\Rightarrow x=-62\). Vậy \(x=-62\)
\(b.2x-41=3x+\left(-23\right)\)
\(\Leftrightarrow2x-3x=-23+41\)
\(\Leftrightarrow-x=18\)
\(\Rightarrow x=-18\). Vậy \(x=-18\)
\(c.4\left(x-3\right)-3\left(x+5\right)=45.\left(-2\right)-34\)
\(\Leftrightarrow4x-12-3x-15=-124\)
\(\Leftrightarrow4x-3x=-124+12+15\)
\(\Rightarrow x=-97\). Vậy \(x=-97\)
\(d.\left(x+3\right)\left(2x-18\right)=0\)
\(\Leftrightarrow\hept{\begin{cases}x+3=0\\2x-18=0\end{cases}\Rightarrow\hept{\begin{cases}x=-3\\x=9\end{cases}}}\). Vậy \(x=-3;9\)
Lời giải:
a.
$21\times 23-3\times 7\times (-17)$
$=21\times 23-21\times (-17)$
$=21\times 23+21\times 17=21\times (23+17)=21\times 40$
$=840$
b.
$42\times 3-7\times [(-34)+18]$
$=7\times 18-7\times (-16)$
$=7\times 18+7\times 16=7\times (18+16)=7\times 34=238$
c.
$=142\times 32+32\times (-7)-13\times 32$
$=32\times (142-7-32)=32\times 103=3296$
d.
$=13\times [(23-17)-(23+17)]$
$=13\times (23-17-23-17)=13\times (-34)=-442$
18:4*3+34-23
= 24,5
18 : 4 * 3 + 34 - 23 = 24,5