Question

[Dương Bảo Trâm]

Tìm x biết (1 phần 4 trừ x) mũ 2 trừ 125% = hỗn số 1 13 phần 16

Answer 1

[Bùi Như Quỳnh]

    (\(\dfrac{1}{4}\) - x)² - 125% = \(1\dfrac{13}{16}\)

⇒ (\(\dfrac{1}{4}\) - x)² - \(\dfrac{5}{4}\) = \(\dfrac{29}{16}\)

⇒ (\(\dfrac{1}{4}\) - x)² = \(\dfrac{29}{16}\) + \(\dfrac{5}{4}\)

⇒ (\(\dfrac{1}{4}\) - x)² = \(\dfrac{49}{16}\)

⇒ (\(\dfrac{1}{4}\) - x)² = \(\left(\dfrac{7}{4}\right)^2\)= \(\left(\dfrac{-7}{4}\right)^2\)

⇒ \(\dfrac{1}{4}\) - x = \(\dfrac{7}{4}\); \(\dfrac{1}{4}\) - x = \(\dfrac{-7}{4}\)

* TH1 :

    \(\dfrac{1}{4}\) - x = \(\dfrac{7}{4}\)

⇒ x = \(\dfrac{1}{4}-\dfrac{7}{4}\)

⇒ x = \(\dfrac{-6}{4}\) = \(\dfrac{-3}{2}\)

* TH2 :

    \(\dfrac{1}{4}\) - x = \(\dfrac{-7}{4}\)

⇒ x = \(\dfrac{1}{4}-\dfrac{-7}{4}\)

⇒ x = \(\dfrac{8}{4}\) = 2

      vậy x ϵ \(\left\{\dfrac{-3}{2};2\right\}\)