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b) \(\left(x-1\right)\left(x^2+x+1\right)-x\left(x+2\right)\left(x-2\right)=5\)
\(x^3-1^3-x\left(x^2-4\right)=5\)
\(x^3-1-\left(x^3-4x\right)=5\)
\(x^3-1-x^3+4x=5\)
\(-1+4x=5\)
\(4x=6\)
\(x=\dfrac{3}{2}\)
\(\left(x-1\right)\left(x^2+x+1\right)-x\left(x+2\right)\left(x-2\right)=5\)
\(\Leftrightarrow x^3-1-x^3+4x=5\)
\(\Leftrightarrow4x=6\)
hay \(x=\dfrac{3}{2}\)
Đặt câu
My father works in the hospital.
-Where does your father work?
Đặt câu
My father works in the hospital.
-Where does your father work ?
chúc bn hk tốt
1/2x^2=4-x
=>x^2=8-2x
=>x^2+2x-8=0
=>(x+4)(x-2)=0
=>x=2; x=-4
Phương trình trạng thái khí lí tưởng:
\(\dfrac{p_1\cdot V_1}{T_1}=\dfrac{p_2\cdot V_2}{T_2}\)
\(\Rightarrow\dfrac{4\cdot6}{293}=\dfrac{p_2\cdot4}{313}\)
\(\Rightarrow p_2=6,41atm\)
Chọn A
Câu 1:
a: \(P=\dfrac{\sqrt{x}}{\sqrt{x}+3}+\dfrac{3x+9}{9-x}+\dfrac{2\sqrt{x}}{\sqrt{x}-3}\)
\(=\dfrac{\sqrt{x}}{\sqrt{x}+3}-\dfrac{3x+9}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}+\dfrac{2\sqrt{x}}{\sqrt{x}-3}\)
\(=\dfrac{\sqrt{x}\left(\sqrt{x}-3\right)-3x-9+2\sqrt{x}\cdot\left(\sqrt{x}+3\right)}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}\)
\(=\dfrac{x-3\sqrt{x}-3x-9+2x+6\sqrt{x}}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}\)
\(=\dfrac{3\sqrt{x}-9}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}=\dfrac{3}{\sqrt{x}+3}\)
b: Thay \(x=4-2\sqrt{3}=\left(\sqrt{3}-1\right)^2\) vào Q, ta được:
\(Q=\dfrac{3}{\sqrt{\left(\sqrt{3}-1\right)^2}-1}=\dfrac{3}{\sqrt{3}-1-1}\)
\(=\dfrac{3}{\sqrt{3}-2}=-3\left(2+\sqrt{3}\right)\)
c: Đặt A=Q:P
\(=\dfrac{3}{\sqrt{x}-1}:\dfrac{3}{\sqrt{x}+3}=\dfrac{\sqrt{x}+3}{\sqrt{x}-1}\)
Để A nguyên thì \(\sqrt{x}+3⋮\sqrt{x}-1\)
=>\(\sqrt{x}-1+4⋮\sqrt{x}-1\)
=>\(4⋮\sqrt{x}-1\)
=>\(\sqrt{x}-1\in\left\{1;-1;2;-2;4;-4\right\}\)
=>\(\sqrt{x}\in\left\{2;0;3;-1;5;-3\right\}\)
=>\(\sqrt{x}\in\left\{2;0;3;5\right\}\)
=>\(x\in\left\{0;4;9;25\right\}\)
Kết hợp ĐKXĐ, ta được: \(x\in\left\{0;4;25\right\}\)