
![A2)\ \ \dfrac{x^2\cdot \sqrt[3]{x\sqrt[5]{x^2}}}{\sqrt[15]{x^4}}=\dfrac{x^2\cdot (x^{1+2/5})^{1/3}}{x^{4/15}}=\dfrac{x^2\cdot (x^{7/5})^{1/3}}{x^{4/15}}=\dfrac{x^2\cdot x^{7/15}}{x^{4/15}}=\\\\\\=x^2\cdot x^{3/15}=x^2\cdot x^{1/5}=x^{2+1/5}=x^{11/5}=\sqrt[5]{x^{11}}\\\\\\A3)\ \ (b^{\sqrt3+1})^{\sqrt3+1}\cdot \dfrac{1}{b^{4+\sqrt3}}=b^{(\sqrt3+1)^2}\cdot \dfrac{1}{b^{4+\sqrt3}}=b^{4+2\sqrt3}\cdot \dfrac{1}{b^{4+\sqrt3}}=b^{\sqrt3}](/tpl/images/1364/2694/b4a4c.png)
![A5)\ \ 2a\sqrt[6]{-a}=\Big[\ -a\geq 0\ \ \to \ \ \ a\leq 0\ \Big]=-\sqrt[6]{-2^6a^6\cdot a}=-\sqrt[6]{-64a^7}\\\\\\A6)\ \ \ a\leq 0\ \ \to \ \ |a|=-a\ \ ;\ \ \ c^5\geq 0\ \ \to \ \ c\geq 0\ \ ,\ \ |c|=c\\\\\sqrt[4]{32a^4b^8c^5}=\sqrt[4]{2^4\cdot 2\cdot a^4\cdot (b^2)^4\cdot c^4\cdot c}=\\\\\\=2\cdot |\underbrace {a}_{\leq 0}|\cdot |\underbrace {b^2}_{\geq 0}|\cdot |\underbrace {c}_{\geq 0}|\cdot \sqrt[4]{2c}=-2\, a\, b^2\, c\cdot \sqrt[4]{2c}](/tpl/images/1364/2694/fbdf7.png)
* * * * * * * * * * * * * * * * * * * * * * * * *
Решите систему уравнений { 3xy -x =5 ; 3xy -y= 4
ответ: (x₁ ; y₁) = ( -5/3 ; -2/3 ) ; ( x₂ ; y₂) = (1 ; 2) .
Объяснение:
{ 3xy -x =5 ; 3xy -y= 4 . ⇔ { 3xy -x-(3xy -y) = 5 - 4 ; 3xy -x =5 . ⇔
{ y=x+1 ; 3xy - x =5 .⇔ { y=x+1 ; 3x(x+1) - x -5 =0 .⇔ { y=x+1 ; 3x²+2x -5 =0 .
3x²+2x -5 =0
D₁= D/4 =( 2/2)² - 3*(-5) =1²+15 =16 = 4² ; x = (-1 ± √D₁)/3
⇒ x₁ = (-1 -4) /3 = - 5/3 ⇒ y₁ = x₁+1 = -5/3+1 = -2/3
x₂ = (-1 +4) /3 = 1 ⇒ y₂ = x₂+1 =1 +1 = 2 .