Từ giả thiết y = \(\frac{x}{4}\) và \(\frac{x^2}{4}=9\) => x = \(\sqrt{36}=6\left(x\ge0\right)\)

y=\(\frac{6}{4}=\frac{3}{2}\)

Vậy : E đúng

Hjhj

Anh thấy thường thường có 4 đáp án , liếc thấy cái cuối cùng đúng nên chọn D

:v

a) \(\left(x+\dfrac{1}{2}\right)^2\)=\(\dfrac{4}{9}=\left(\dfrac{2}{3}\right)^2=\left(\dfrac{-2}{3}\right)^2\)
\(\Leftrightarrow\left\{{}\begin{matrix}x+\dfrac{1}{2}=\dfrac{2}{3}\\x+\dfrac{1}{2}=\dfrac{-2}{3}\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{1}{6}\\x=\dfrac{-7}{6}\end{matrix}\right.\)
b)\(|x+\dfrac{97}{306}|\)\(\)\(+5=-1\)
\(\Leftrightarrow|x+\dfrac{97}{106}|=-1-5=-1+\left(-5\right)=-6\)
\(\Rightarrow x\in\left\{\varnothing\right\}\)
Bài 2: Gọi 3 số lần lượt là a,b,c(a,b,c<481)
Ta có: \(a^2+b^2+c^2=481\left(1\right)\)
\(\dfrac{4}{3}a=b\Leftrightarrow a=\dfrac{3b}{4}\left(2\right)\)
\(\dfrac{3}{4}c=b\Leftrightarrow c=\dfrac{4b}{3}\left(3\right)\)
Từ \(\left(1\right),\left(2\right)va\left(3\right)\)ta có: \(\left(\dfrac{3b}{4}\right)^2+b^2+\left(\dfrac{4b}{3}\right)^2\)\(=481\)
\(\Rightarrow b=12\)
\(\Rightarrow a=\dfrac{3b}{4}=\dfrac{3.12}{4}=\dfrac{36}{4}=9\)
\(\Rightarrow c=\dfrac{4b}{3}=\dfrac{4.12}{3}=\dfrac{48}{3}=16\)
Tiên T.I.C.K Hiền nhoa!!^_^

Giải:

a) \(\left(x+2\right)^5=\left(x+2\right)^2\)

Vì \(x+2=x+2\)

Mà \(5\ne2\)

\(\Leftrightarrow\left(x+2\right)=\left\{0;1\right\}\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+2=0\\x+2=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\x=-1\end{matrix}\right.\)

Vậy \(x=-2\) hoặc \(x=-1\)

b) \(2^{3x+4}=4^{x+8}\)

\(\Leftrightarrow2^{3x+4}=\left(2^2\right)^{x+8}\)

\(\Leftrightarrow2^{3x+4}=2^{2x+16}\)

Vì \(2=2\)

Nên \(3x+4=2x+16\)

\(\Leftrightarrow3x-2x=16-4\)

\(\Leftrightarrow x=12\)

Vậy \(x=12\).

c) \(3^{x+2}=9^{x-1}\)

\(\Leftrightarrow3^{x+2}=\left(3^2\right)^{x-1}\)

\(\Leftrightarrow3^{x+2}=3^{2x-2}\)

Vì \(3=3\)

Nên \(x+2=2x-2\)

\(\Leftrightarrow2x-2=2+2\)

\(\Leftrightarrow x=4\)

Vậy \(x=4\).

d) \(9^{x-2}=27^{x-4}\)

\(\Leftrightarrow\left(3^2\right)^{x-2}=\left(3^3\right)^{x-4}\)

\(\Leftrightarrow3^{2x-4}=3^{3x-12}\)

Vì \(3=3\)

Nên \(2x-4=3x-12\)

\(\Leftrightarrow x=8\)

Vậy \(x=8\).

Chúc bạn học tốt!!!

a)\(\left(x+2\right)^5=\left(x+2\right)^2\)

=>\(\left(x+2\right)^5-\left(x+2\right)^2=0\)

=>\(\left(x+2\right)^2\left(\left(x+2\right)^3-1\right)=0\)

=>\(\left(x+2\right)^2=0\) hoặc \(\left(x+2\right)^3-1=0\)

=>\(x+2=0\) hoặc \(\left(x+2\right)^3=1\)

=>\(x=-2\) hoặc \(x+2=1\)

=>\(x=-2hoặcx=-1\)

Vậy...

Các câu sau tương tự

là sao bạn

\(\left(x^2-4\right)\left(x^2+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2-4=0\\x^2+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x^2=0\Rightarrow x=\pm2\\x^2+5=0\Rightarrow x\left(loại\right)\end{matrix}\right.\)

cm: 5=4 là sai p ko

4^2-2*4*9/2 =(4-2*4*9/2)^2 là sai

suy ra 4=5 là sai

mk cs kq r

chờ tí

b: 2x-3<0

=>2x<3

hay x<3/2

c: \(\left(2x-4\right)\left(9-3x\right)>0\)

=>(x-2)(x-3)<0

=>2<x<3

d: \(\dfrac{2}{3}x-\dfrac{3}{4}>0\)

=>2/3x>3/4

hay x>9/8