a) \(\Rightarrow\left(n-1\right)+3⋮\left(n-1\right)\)

\(\Rightarrow\left(n-1\right)\inƯ\left(3\right)=\left\{-3;-1;1;3\right\}\)

Do \(n\in N\)

\(\Rightarrow n\in\left\{0;2;4\right\}\)

b) \(\Rightarrow2\left(n+1\right)+3⋮\left(n+1\right)\)

\(\Rightarrow\left(n+1\right)\inƯ\left(3\right)=\left\{-3;-1;1;3\right\}\)

Do \(n\in N\Rightarrow n\in\left\{0;2\right\}\)

Câu 1:

\(v_{tb}=\dfrac{S}{t_1+t_2}\Rightarrow54=\dfrac{162}{2t}\Rightarrow t=\dfrac{3}{2}\left(h\right)\)

\(S_1=t.v_1=\dfrac{3}{2}.45=\dfrac{135}{2}\left(km\right)\)

\(v_2=\dfrac{S_2}{t}=\dfrac{S-S_1}{t}=\dfrac{162-\dfrac{135}{2}}{\dfrac{3}{2}}=63\left(\dfrac{km}{h}\right)\)

a) \(A=2,7+\left|x-1,5\right|\ge2,7\)

\(minA=2,7\Leftrightarrow x=1,5\)

b) \(B=\left|4,1+x\right|-6,3\ge-6,3\)

\(minB=-6,3\Leftrightarrow x=-4,1\)

\(\left\{{}\begin{matrix}S_1=t.v_1=58t\\S_2=t.v_2=42t\end{matrix}\right.\)

\(\Rightarrow S_1+S_2=58t+42t\Rightarrow100t=120\Rightarrow t=1,2\left(h\right)\)

\(S_1=t.v_1=1,2.58=69,6\left(km\right)\)

Bài 1:

a) \(=5\sqrt{3}-4\sqrt{3}+3\sqrt{3}=4\sqrt{3}\)

b) \(=\dfrac{1}{\left(a-2\right)\left(a+2\right)}.\left(a-2\right).3\sqrt{2}=\dfrac{3\sqrt{2}}{a+2}\)

Bài 2:

a) \(pt\Leftrightarrow\left|x-2\right|=10\Leftrightarrow\left[{}\begin{matrix}x-2=10\\x-2=-10\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-8\end{matrix}\right.\)

b) ĐKXĐ: \(x\ge-1\)

\(pt\Leftrightarrow2\sqrt{x+1}=6\Leftrightarrow\sqrt{x+1}=3\)

\(\Leftrightarrow x+1=9\Leftrightarrow x=8\left(tm\right)\)

Mỗi lần đăng 1-2 câu thôi nha bạn

a) ĐKXĐ: \(-5x+10\ge0\Leftrightarrow5x\le10\Leftrightarrow x\le2\)

b) ĐKXĐ: \(3-6x< 0\Leftrightarrow6x>3\Leftrightarrow x>\dfrac{1}{2}\)

A