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\(\dfrac{5^5}{5^x}=5^{18}\)
\(\Rightarrow5^x=5^5:5^{18}\)
\(\Rightarrow5^x=5^{-13}\)
\(\Rightarrow x=-13\)
\(\dfrac{x-7}{6}=\dfrac{3}{2\left(x-7\right)}\)
\(\Rightarrow2\left(x-7\right)\left(x-7\right)=18\)
\(\Rightarrow2\left(x-7\right)^2=18\)
\(\Rightarrow\left(x-7\right)^2=9\)
\(\Rightarrow\left[{}\begin{matrix}x-7=-3\\x-7=3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=10\end{matrix}\right.\)
\(\frac{5}{6} + \left [ \frac{2}{3}x - \left ( \frac{-7}{12} \right ) \right ]= \frac{1}{2}\)
\(\frac{2}{3}x + \frac{7}{12}= -\frac{1}{3}\)
\(\frac{2}{3}x = - \frac{1}{3} - \frac{7}{12}\)
\(\frac{2}{3}x= -\frac{11}{12}\)
\(x= - \frac{11}{8}\)
Vậy \(x= - \frac{11}{8}\)
b) \(\frac{x}{15} + 1,2= \frac{1}{3}\)
\(\frac{x}{15}= \frac{1}{3} - 1,2\)
\(\frac{x}{15}=- \frac{13}{15}\)
x = - 13
Vậy x = - 13
câu c pn coi lại đề nhé
d) 3 + \(\left | x - 1,34 \right |\) = 5
\(\left | x - 1,34 \right |\) = 5 - 3
\(\left | x - 1,34 \right |\) = 2
\(\Leftrightarrow \begin{bmatrix} x - 1,34 = 2 & & \\ x - 1,34= 2 & & \end{bmatrix}\) \(\Leftrightarrow \begin{bmatrix} x= 3,34 & & \\ x = - 0,66 & & \end{bmatrix}\)
(bỏ dấu ngoặc bên phải nha pn)
Vậy x = 3,34; x = - 0,66
câu e pn lm tương tự
\(\left(x^5\right)^2=\dfrac{x^{18}}{x^7}\left(đk:x\ne0\right)\)
\(\Rightarrow x^{10}=x^{11}\)
\(\Rightarrow x^{11}-x^{10}=0\)
\(\Rightarrow x^{10}\left(x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\left(ktm\right)\\x=1\left(tm\right)\end{matrix}\right.\)
X+9/x+5=2/7
<=>(x+9).7=(x+5).2
<=>7x+63=2x+10
<=>7x-2x=10-63
<=>5x=-53
<=>x=-53/5
b)x^2-xy=-18<=>x(x-y)=-18
<=>3x=-18<=>x=-6
a. -3/4 x 12/-5 x (-25/6)=-15/2
b. -2 x -38/21 x -7/4 x (-3/8)=-19/8
c. (11/12: 33/16) x 3/5=4/15
d. 7/23 x [(-8/6)- 45/18]=-7/6
b) 2(x+1)+42=24
2(x+1)+16=16
2(x+1) = 16-16
2(x+1) = 0
x+1=2x0
x+1=0
x=0-1
x = -1
(x5)2=x18x7(đk:x≠0)(x5)2=x18x7(đk:x≠0)
⇒x10=x11⇒x10=x11
⇒x11−x10=0⇒x11−x10=0
⇒x10(x−1)=0⇒x10(x−1)=0
⇒[x=0(ktm)x=1(tm)
(x4)3=x18x7(x4)3=x18x7
⇔ x12=x11x12=x11
⇔ x12−x11=0x12−x11=0
⇔ x11.(x−1)=0x11.(x−1)=0
⇔ [x11=0x−1=0[x11=0x−1=0
⇔ [x=0x=0+1=1[x=0x=0+1=1
Vậy xx ∈ {0;1}