a) 4x² - 25 = 0

    4x²            = 25

    ( 2x)²     =  5²

     2x        = 5

=>  x         = 5/2

1a) 4x² - 25 = 0 =>  4x² = 25 => x² = \(\frac{25}{4}\)= \(\left(\frac{5}{2}\right)^2\)=> x = \(\frac{5}{2}\)

a , ( 2x - 5 ) ( 2x + 5 ) = 0 .... tự làm nhé
 

1, 

a, \(\left(2x-5\right)\cdot\left(2x+5\right)=0\)

\(x=\frac{5}{2}\)

x\(=-\frac{5}{2}\)

b \(\left(x^3-x^2\right)^2-\left(2x-2\right)^2\)=0

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

x=2

x=2/3

2, 

a (3x^2)^3-(2x)^3

(3x^2-2x)(9x^4+6x^3+4x^2)

\(4x^2-25=0\)

\(\left(2x-5\right)\left(2x+5\right)=0\)

\(\Rightarrow\orbr{\begin{cases}2x-5=0\\2x+5=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{5}{2}\\x=-\frac{5}{2}\end{cases}}\)

Vậy \(\orbr{\begin{cases}x=\frac{5}{2}\\x=-\frac{5}{2}\end{cases}}\)

\(27x^6-8x^3=\left(3x^2\right)^3-\left(2x\right)^3=\left(3x^2-2x\right)\left[\left(3x^2\right)^2+3x^2.2x+\left(2x\right)^2\right]=x^3.\left(3x-2\right).\left(3x^2+6x+4\right)\)

131947695749 kb nhé

tk mk

ủng hộ mk

và ARMY nè

111111111111 + 20836584638 = 131947695700000000000

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Đừng hòng nha!!!  >_<