Question

Tìm x:

\( \left(3x-1\right).\left(3x+1\right)-9.\left(x+2\right).\left(x-2\right)=-37\)

Answer 1

\(\left(3x-1\right)\left(3x+1\right)-9\left(x+2\right)\left(x-2\right)=-37\\ \left(9x^2-1\right)-9\left(x^2-4\right)=-37\\ 9x^2-1-9x^2+36=-37\\ 35=-37\left(L\right)\)

Vậy không có x thỏa mãn

Answer 2

\(9x^2-1-9.\left(x^2-4\right)=-37\\ 9x^2-1-9x^2+36=-37\\ 35=-37\left(voli\right)\)

Vậy pt vô no

Answer 3

Ta có: `(a-b)(a+b)=a^2-b^2`.

`(3x-1)(3x+1) - 9(x+2)(x-2) = -37`

`9x^2 - 1 - 9(x^2-4) = 37`

`9x^2 - 1 - 9x^2 + 36 = 37`

`35 = 37`( vô lý)

`=> x = cancel o`.