Câu 1: 27-(14-x)=-x+3
Câu 2: 27^x*3^x+3^4*x+1=4
mình cần luôn nha! Ai giúp mik cho 10 like
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A. x = 2
B. \(\dfrac{3}{8}=\dfrac{6}{x}\)\(\Leftrightarrow x=\dfrac{6.8}{3}=16\)
C. x = 3
D. \(x=\dfrac{4.6}{8}=3\)
E. \(x=\dfrac{7}{3}\)
G.\(\dfrac{14}{13}=\dfrac{28}{10-x}\)
<=>\(14\left(10-x\right)=364\)
<=> 10 - x = 26
<=> x = -16
H. \(3\left(x+2\right)=4\left(x-5\right)\)
<=> 3x + 6 = 4x - 20
<=> -x = -26
<=> x = 26
K. \(\dfrac{x}{2}=\dfrac{8}{x}\)
<=> \(x^2=16\)
<=> \(\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)
M. \(\left(x-2\right)^2=100\)
<=> \(\left[{}\begin{matrix}x-2=10\\x-2=-10\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-8\end{matrix}\right.\)
a=2
b=16
c=3
d=3
mik chỉ biết thế này thôi(ko chắc đúng=3)
a)12 x 18 + 14 x 3 - 255 : 17=25.58823529411765
b)68 + 42 x 5 - 625 : 25=5182
c) 13+ 21 x 5 - (198 : 11 - 8)=108
d) 1188 - 4 x (27 + 90 + 73 :10 )=
e) 5 + 8 + 11 + 14 +......+ 38 + 41=
f) 51 - 49 + 55 - 53 + 59 - 56 + 63 - 61 + 65=74
có mấy câu mình ko biết,xin lỗi bạn
a) \(3\left(2x-5\right)+125=134\)
\(\Leftrightarrow3\left(2x-5\right)=9\)
\(\Leftrightarrow2x-5=3\)
\(\Leftrightarrow2x=8\Leftrightarrow x=4\)
b) \(\left(2x+5\right)+\left(2x+3\right)+\left(2x+1\right)=27\)
\(\Leftrightarrow6x+9=27\)
\(\Leftrightarrow6x=18\Leftrightarrow x=3\)
d) \(27\left(x-27\right)-27=0\)
\(\Leftrightarrow27\left(x-27\right)=27\)
\(\Leftrightarrow x-27=1\Leftrightarrow x=28\)
a) Ta có: \(\left(x-3\right)\left(1-x\right)-2\)
\(=-x^2+4x-3-2\)
\(=-\left(x^2-4x+4\right)-1\)
\(=-\left(x-2\right)^2-1\le-1< 0\left(\forall x\right)\)
=> đpcm
b) Ta có: \(\left(x+4\right)\left(2-x\right)-10\)
\(=-x^2-2x+8-10\)
\(=-\left(x^2+2x+1\right)-1\)
\(=-\left(x+1\right)^2-1\le-1< 0\left(\forall x\right)\)
=> đpcm
b) \(\left(x+4\right)\left(2-x\right)-10=-x^2-4x+2x+8-10\)
\(=-x^2-2x-2=-x^2-2x-1-1\)
\(=-\left(x^2+2x+1\right)-1=-\left(x+1\right)^2-1\)
Vì \(\left(x+2\right)^2\ge0\forall x\)\(\Rightarrow-\left(x+2\right)^2\le0\forall x\)
\(\Rightarrow-\left(x+2\right)^2-1\le-1\forall x\)
\(\Rightarrow\left(x+4\right)\left(2-x\right)-10\le-1\forall x\)
hay \(\left(x+4\right)\left(2-x\right)-10\)luôn âm với mọi x ( đpcm )
a. $\dfrac{14}{15}+\dfrac{2}{11}+\dfrac{1}{15}+\dfrac{4}{11}+\dfrac{10}{22}$
$=(\dfrac{14}{15}+dfrac{1}{15})+(\dfrac{2}{11}+\dfrac{4}{11}+\dfrac{10}{22})$
$=1+1=2$
b. $74\times43-43+27\times43$
$=(74-1+27)\times43$
$=100\times43=4300$
\(a)\dfrac{14}{15}+\dfrac{2}{11}+\dfrac{1}{15}+\dfrac{4}{11}+\dfrac{10}{22}\)
\(=\left(\dfrac{14}{15}+\dfrac{1}{15}\right)+\dfrac{2}{11}+\dfrac{4}{11}+\dfrac{5}{11}\)
\(=1+1=2\)
\(b)74\times43-43+27\times43\)
\(=43\times\left(74-1+27\right)\)
\(=43\times100=4300\)
a) x=-213:(1+2+3+4+...+100)<=>x=-213/100
b) x-x=-1/3-2/4 <=> 0= -5/6 (vô lý )
c) x=-0,8119408369
d) x= 0.0258907758
a; \(\dfrac{2}{3}\)\(x\) - \(\dfrac{3}{2}\)\(x\) = \(\dfrac{5}{12}\)
(\(\dfrac{2}{3}\) - \(\dfrac{3}{2}\))\(x\) = \(\dfrac{5}{12}\)
- \(\dfrac{5}{6}\)\(x\) = \(\dfrac{5}{12}\)
\(x\) = \(\dfrac{5}{12}\) : (- \(\dfrac{5}{6}\))
\(x=\) - \(\dfrac{1}{2}\)
Vậy \(x=-\dfrac{1}{2}\)
b; \(\dfrac{2}{5}\) + \(\dfrac{3}{5}\).(3\(x\) - 3,7) = \(\dfrac{-53}{10}\)
\(\dfrac{3}{5}\).(3\(x\) - 3,7) = \(\dfrac{-53}{10}\) - \(\dfrac{2}{5}\)
\(\dfrac{3}{5}\).(3\(x\) - 3,7) = - \(\dfrac{57}{10}\)
3\(x\) - 3,7 = - \(\dfrac{57}{10}\) : \(\dfrac{3}{5}\)
3\(x\) - 3,7 = - \(\dfrac{19}{2}\)
3\(x\) = - \(\dfrac{19}{2}\) + 3,7
3\(x\) = - \(\dfrac{29}{5}\)
\(x\) = - \(\dfrac{29}{5}\) : 3
\(x\) = - \(\dfrac{29}{15}\)
Vậy \(x\) \(\in\) - \(\dfrac{29}{15}\)
\(27-\left(14-x\right)=-x+3\)
\(\Leftrightarrow\)\(27-14+x=-x+3\)
\(\Leftrightarrow\)\(13+x=-x+3\)
\(\Leftrightarrow\)\(2x=-10\)
\(\Leftrightarrow\)\(x=-5\)
Vậy...
Câu 1 :
=> 27-14+x = -x+3
=> 13+x = -x+3
=> x = -x+3-13 = -x-10
=> 10 = -x-x = -2x
=> x = 10 : (-2) = -5
Vậy x = -5
Tk mk nha