Tìm số hữu tỉ x, biết:
\(\left(x-2\right)\left(x+2\right)\left(4-x\right)\left[\left(x-1\right)^2\right]\le0\)
1 tick nha
tìm số hữu tỉ x biết :
a)|1-2x|>7
b)\(\frac{-5}{x-3}< 0\)
c)\(\left(x-2\right)\left(x+2\right)\left(4-x\right)\left(x-1\right)^2\) \(\le0\)
a/ \(\left|1-2x\right|>7\Leftrightarrow\left[{}\begin{matrix}1-2x=7\\1-2x=-7\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x< -6\\2x< 8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x< -3\\x< 4\end{matrix}\right.\)
b/ \(\dfrac{-5}{x-3}< 0\Leftrightarrow x-3>0\) ( vì -5<0)
\(\Leftrightarrow x>3\)
Tìm các cặp số x,y
\(\left(x-3\right)^2+\left(2y-1\right)^2=0\)
\(\left(4x-3\right)^4+\left(y+2\right)^2\le0\)
(\(x-3\))2 + (2y - 1)2 = 0
(\(x\) - 3)2 ≥ 0 ∀ \(x\)
(2y - 1)2 ≥ 0 ∀ y
⇔ (\(x\) - 3)2 + (2y - 1)2= 0
⇔ \(\left\{{}\begin{matrix}x-3=0\\3y-1=0\end{matrix}\right.\)
\(\Leftrightarrow\) \(\left\{{}\begin{matrix}x=2\\y=\dfrac{1}{3}\end{matrix}\right.\)
(4\(x-3\))4 + (y + 2)2 ≤ 0
(4\(x\) - 3)4 ≥ 0 ∀ \(x\)
(y + 2)2 ≥ 0 ∀ y
⇔(4\(x\) - 3)4 + (y+2)2 ≥ 0
⇔ (4\(x\) - 3)4 + (y + 2)2 ≤ 0 ⇔
⇔\(\left\{{}\begin{matrix}4x-3=0\\y+2=0\end{matrix}\right.\)
⇔ \(\left\{{}\begin{matrix}x=\dfrac{3}{4}\\y=-2\end{matrix}\right.\)
Tìm x biết:\(\left(x^2-1\right)\cdot\left(x^2-3\right)\left(x^2-5\right)\left(x^2-7\right)\le0\)
Tìm x,y biết :
a) \(\left|3.x-\dfrac{1}{2}\right|+\left|\dfrac{1}{4}.y+\dfrac{3}{5}\right|\)= 0
b)\(\left|\dfrac{3}{2}.x+\dfrac{1}{9}\right|+\left|\dfrac{5}{7}.y-\dfrac{1}{2}\right|\le0\)
a) \(\left|3x-\dfrac{1}{2}\right|+\left|\dfrac{1}{4}y+\dfrac{3}{5}\right|=0\)
Do \(\left|3x-\dfrac{1}{2}\right|,\left|\dfrac{1}{4}y+\dfrac{3}{5}\right|\ge0\forall x,y\)
\(\Rightarrow\left\{{}\begin{matrix}3x-\dfrac{1}{2}=0\\\dfrac{1}{4}y+\dfrac{3}{5}=0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{1}{6}\\y=-\dfrac{12}{5}\end{matrix}\right.\)
b) \(\left|\dfrac{3}{2}x+\dfrac{1}{9}\right|+\left|\dfrac{5}{7}y-\dfrac{1}{2}\right|\le0\)
Do \(\left|\dfrac{3}{2}x+\dfrac{1}{9}\right|,\left|\dfrac{5}{7}y-\dfrac{1}{2}\right|\ge0\forall x,y\)
\(\Rightarrow\left\{{}\begin{matrix}\dfrac{3}{2}x+\dfrac{1}{9}=0\\\dfrac{5}{7}y-\dfrac{1}{2}=0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x=-\dfrac{2}{27}\\y=\dfrac{7}{10}\end{matrix}\right.\)
tìm x biết \(8\left(x+\frac{1}{x}\right)^2+4\left(x^2+\frac{1}{x^2}\right)^2-4\left(x^2+\frac{1}{x^2}\right)\left(x+\frac{1}{x}\right)^2=\left(x+4\right)^2...\)
ai làm nhanh và đúng thì đc 3 tick nha
đó chính là -4 minh khong muon giai ra ta lau lam ban
rút 4 ra ngoài nhan bạn 4(2(x+1/x)^2+(x^2+1/x^2)^2-(x^2+1/x^2)(x+1/x)^2=(x+4)^2
mik xét cái này cho dễ nhìn nhan
2(x+1/x)^2-(x^2+1/x^2)(x+1/x)^2
= (x+1/x)^2(2-x^2-1/x^2)
= -(x+1/x)^2(x^2-2+1/x^2)
= -(x+1/x)^2(x-1/x)^2=-(x^2-1/x^2)^2
thế ở trên ta có
4(-(x^2-1/x^2)^2+(x^2+1/x^2)^2)=(x+4)^2
4(-x^4+2-1/x^4+x^4+2+1/x^4)=x^2+8x+16
4.4=x^2+8x+16
suy ra x^2+8x=0
x(x+8)=0
suy ra x=0 hoặc x=-8
mak nhìn để bài thì x=0 ko được nên x=-8
tìm x biết
\(\left(x^2-1\right)\left(x^2-3\right)\left(x^2-5\right)\left(x^2-7\right)\le0\)
tìm các khoảng và nửa khoảng mà trên đó mỗi hàm số liên tục:
f(x)=\(\left\{{}\begin{matrix}2x+1\left(0< x< 2\right)\\2\left(x\ge2\right)\\\left(x-1\right)^2\left(x\le0\right)\end{matrix}\right.\)
f(x)=\(\left\{{}\begin{matrix}\dfrac{x^2-3x+2}{x-1}\left(x\ne1\right)\\\dfrac{-1}{2}\left(x=1\right)\end{matrix}\right.\)
\(f\left(x\right)=\left\{{}\begin{matrix}\dfrac{\sqrt{x+4}-2}{x}\left(x>0\right)\\mx^2+2m+\dfrac{1}{4}\left(x\le0\right)\end{matrix}\right.\) (m là tham số). tìm m để hàm số liên tục tại x=0
\(\lim\limits_{x\rightarrow0^+}f\left(x\right)=\lim\limits_{x\rightarrow0^+}\dfrac{\sqrt{x+4}-2}{x}=\lim\limits_{x\rightarrow0^+}\dfrac{x}{x\left(\sqrt{x+4}+2\right)}=\lim\limits_{x\rightarrow0^+}\dfrac{1}{\sqrt{x+4}+2}=\dfrac{1}{4}\)
\(f\left(0\right)=\lim\limits_{x\rightarrow0^-}f\left(x\right)=\lim\limits_{x\rightarrow0^-}\left(mx^2+2m+\dfrac{1}{4}\right)=2m+\dfrac{1}{4}\)
Hàm liên tục tại x=0 khi: \(\lim\limits_{x\rightarrow0^+}f\left(x\right)=\lim\limits_{x\rightarrow0^-}f\left(x\right)=f\left(0\right)\)
\(\Leftrightarrow2m+\dfrac{1}{4}=\dfrac{1}{4}\Leftrightarrow m=0\)
tìm x,biết:
\(^{\left(x^2-1\right)\left(x^2-3\right)\left(x^2-5\right)\left(x^2-7\right)\le0}\)