Đáp án:
Giải thích các bước giải:
Bài 2:
a) $\frac{1}{2}$ + $\frac{2}{3}$ : (x - 1) = $\frac{3}{4}$
$\frac{2}{3}$ : (x - 1) = $\frac{3}{4}$ - $\frac{1}{2}$
$\frac{2}{3}$ : (x - 1) = $\frac{1}{4}$
(x - 1) = $\frac{2}{3}$ : $\frac{1}{4}$
⇒ x - 1 = $\frac{8}{3}$
⇒ x = $\frac{8}{3}$ + 1
⇒ x = $\frac{11}{3}$
Vậy x = $\frac{11}{3}$
b) 5 . 4 - 3|x - $\frac{21}{10}$| = 0
20 - 3|x - $\frac{21}{10}$| = 0
3|x - $\frac{21}{10}$| = 20
|x - $\frac{21}{10}$| = $\frac{20}{3}$
⇒\(\left[ \begin{array}{l}x-\frac{21}{10}=\frac{20}{3}\\x-\frac{21}{10}=-\frac{20}{3}\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=\frac{20}{3}+\frac{21}{10} \\x=-\frac{20}{3}+\frac{21}{10}\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=\frac{263}{30}\\x=-\frac{137}{30}\end{array} \right.\)
Vậy x = $\frac{263}{30}$ hoặc x = $-\frac{137}{30}$
c) (2x - 3)² = $\frac{36}{25}$
(2x - 3)² = $(\frac{6}{5})^{2}$
⇒ 2x - 3 = $\frac{6}{5}$
2x = $\frac{6}{5}$ + 3
2x = $\frac{21}{5}$
⇒ x = $\frac{21}{5}$ : 2
⇒ x = $\frac{21}{10}$
Vậy x = $\frac{21}{10}$
d) 10$\sqrt{x}$ - 5 = 25
10$\sqrt{x}$ = 30
$\sqrt{x}$ = 30 : 10
$\sqrt{x}$ = 3
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