1) x³ - 3x² = 0

<=> x²( x - 3 ) = 0

<=> \(\orbr{\begin{cases}x^2=0\\x-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=3\end{cases}}\)

2) 5x( x - 2020 ) - x + 2020 = 0

<=> 5x( x - 2020 ) - ( x - 2020 ) = 0

<=> ( x - 2020 )( 5x - 1 ) = 0

<=> \(\orbr{\begin{cases}x-2020=0\\5x-1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2020\\x=\frac{1}{5}\end{cases}}\)

3) ( 3x - 5 )² = ( x + 1 )²

<=> ( 3x - 5 )² - ( x + 1 )² = 0

<=> [ ( 3x - 5 ) - ( x + 1 ) ][ ( 3x - 5 ) + ( x + 1 ) ] = 0

<=> ( 3x - 5 - x - 1 )( 3x - 5 + x + 1 ) = 0

<=> ( 2x - 6 )( 4x - 4 ) = 0

<=> \(\orbr{\begin{cases}2x-6=0\\4x-4=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}\)

4) ( x² - 2x )² - 2( x - 1 )² + 2 = 0

<=> ( x² - 2x )² - 2( x² - 2x + 1 ) + 2 = 0

<=> ( x² - 2x )² - 2x² + 4x - 2 + 2 = 0

<=> ( x² - 2x )² - 2( x² - 2x ) = 0

<=> ( x² - 2x )( x² - 2x - 2 ) = 0

<=> \(\orbr{\begin{cases}x^2-2x=0\\x^2-2x-2=0\end{cases}}\)

+) x² - 2x = 0 <=> x( x - 1 ) = 0 <=> \(\orbr{\begin{cases}x=0\\x-1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\)

+) x² - 2x - 2 = 0 

<=> x² - 2x + 1 - 3 = 0

<=> ( x² - 2x + 1 ) = 3

<=> ( x - 1 )² = ( ±√3 )²

<=> \(\orbr{\begin{cases}x-1=\sqrt{3}\\x-1=-\sqrt{3}\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1+\sqrt{3}\\x=1-\sqrt{3}\end{cases}}\)

\(\left(x+1\right)^3=27\)

\(\left(x+1\right)^3=3^3\)

\(\Rightarrow x+1=3\)

\(x=2\)

\(\left(x+1\right)^3=27\)

\(< =>\left(x+1\right)^3=3.3.3=3^3\)

\(< =>x+1=3< =>x=3-1=2\)

\(\left(2x+3\right)^3=9.81\)

\(< =>\left(2x+3\right)^3=9.9.9\)

\(< =>\left(2x+3\right)^3=9^3\)

\(< =>2x+3=9< =>2x=6\)

\(< =>x=\frac{6}{2}=3\)

giúp mình bài này đi

21.73 + 27 . 21

Bài 1 :

\(M=\dfrac{30-2^{20}}{2^{18}}=\dfrac{2.15-2^{20}}{2^{18}}=\dfrac{15}{2^{17}}-2^2=\dfrac{15}{2^{17}}-4< 0\left(\dfrac{15}{2^{17}}< 1\right)\)

\(N=\dfrac{3^5}{1^{2021}+2^3}=\dfrac{3^5}{9}=\dfrac{3^5}{3^2}=3^3=27\)

\(\Rightarrow M< N\)

Bài 3 :

a) \(t^2+5t-8\) khi \(t=2\)

\(=5^2+2.5-8\)

\(=25+10-8\)

\(=27\)

b) \(\left(a+b\right)^2-\left(b-a\right)^3+2021\left(1\right)\)

\(\left\{{}\begin{matrix}a=5\\b=a+1=6\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}a+b=11\\b-a=1\end{matrix}\right.\)

\(\left(1\right)=11^2-1^3+2021=121-1+2021=2141\)

c) \(x^3-3x^2y+3xy^2-y^3=\left(x-y\right)^3\left(1\right)\)

\(\left\{{}\begin{matrix}x=3\\y=2\end{matrix}\right.\) \(\Rightarrow x-y=1\)

\(\left(1\right)=1^3=1\)

Bài 2 :

a) \(...=2^3\left(19-14\right)+1=8.5+1=41\)

b) \(...=100-\left[60:\left(5^2-15\right)\right]=100-\left[60:10\right]=100-6=94\)

c) \(...=160:\left[17+\left(9.5-\left(14+2^3\right)\right)\right]=160:\left[17+\left(45-22\right)\right]=160:\left[17+23\right]=160:40=4\)

d) \(...=798+100\left[16-2\left(25-22\right)\right]=798+100\left[16-2.3\right]=798+100.10=798+1000=1798\)

Bài 2 : 

a, \(x^2-4x=0\Leftrightarrow x\left(x-4\right)=0\Leftrightarrow x=0;4\)

b, \(5x\left(x-2020\right)-x+2020=0\)

\(\Leftrightarrow5x\left(x-2020\right)-\left(x-2020\right)=0\Leftrightarrow\left(5x-1\right)\left(x-2020\right)=0\)

\(\Leftrightarrow x=\frac{1}{5};2020\)

c, \(\left(4x+5\right)^2-\left(2x-1\right)^2=0\)

\(\Leftrightarrow16x^2+40x+25-\left(4x^2-4x+1\right)=0\)

\(\Leftrightarrow12x^2+44x+24=0\Leftrightarrow4\left(x+3\right)\left(3x+2\right)=0\)

\(\Leftrightarrow x=-3;-\frac{2}{3}\)

a,x²-4x=0

= x.(x-4)=0

=> x=0 hoặc x-4=0

=>x=0 hoặc x=4

a. x² - 4x = 0

<=> x ( x - 4 ) = 0

<=>\(\orbr{\begin{cases}x=0\\x=-4\end{cases}}\)

b. 5x ( x - 2020 ) - x + 2020 = 0

<=> 5x ( x - 2020 ) - ( x - 2020 ) = 0

<=> ( 5x - 1 ) ( x - 2020 ) = 0

<=>\(\orbr{\begin{cases}5x-1=0\\x-2020=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=\frac{1}{5}\\x=2020\end{cases}}\)

c. ( 4x + 5 )² - ( 2x - 1 )² = 0

<=> 16x² + 40x + 25 - 4x² + 4x - 1 = 0

<=> 12x² + 44x + 24 = 0

<=> 4 ( 3x² + 11x + 6 ) = 0

<=> ( 3x² + 9x ) + ( 2x + 6 ) = 0

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

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

<=>\(\orbr{\begin{cases}3x+2=0\\x+3=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=-\frac{2}{3}\\x=-3\end{cases}}\)

d. x² + 6x - 8 = 0

<=> x² + 6x + 9 = 17

<=> ( x + 3 )² = 17 

<=>\(\orbr{\begin{cases}x+3=\sqrt{17}\\x+3=-\sqrt{17}\end{cases}}\)<=>\(\orbr{\begin{cases}x=-3+\sqrt{17}\\x=-3-\sqrt{17}\end{cases}}\)

e. 4x² + 2x - 6 = 0

<=> 2 ( 2x² + x - 3 ) = 0

<=> ( 2x² + 3x ) - ( 2x + 3 ) = 0

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

<=> ( x - 1 ) ( 2x + 3 ) = 0

<=>\(\orbr{\begin{cases}x-1=0\\2x+3=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=1\\x=-\frac{3}{2}\end{cases}}\)

a.  64.4^x=4⁵

4³.4^x=4⁵

4^x=4⁵:4³

4^x=4²

x=2

có ai biết hoặc là fan gacha life không làm ơn kết bạn với mình đi team gacha life của mình đang thiếu người

a)<=>

A,=(x+y)(x-y)=x^2-y^2

x=(-1/2)^5:(1/2)^4=-1/2

x^2=1/4

y=8^2/(-2)^5=-2

y^2=4

A=1/4-4=-15/4