Câu hỏi của Park Chanyeol

Question

Tìm x biết

a) 7 - $\sqrt{x}$ = 0                                   d) 4x2 -1 =0

b)5$\sqrt{x}$ + 1 = 40                               e) $\sqrt{x+1}$ - 2 = 0

c)$\dfrac{5}{12}$$\sqrt{x}$ -...

Đời về cơ bản là buồn...... · Accepted Answer

a) $7-\sqrt{x}=0$

$\Rightarrow\sqrt{x}=7$

$\Rightarrow x=\left(\sqrt{7}\right)^2$

b) $5\sqrt{x}+1=40$

$\Rightarrow5\sqrt{x}=39$

$\Rightarrow\sqrt{x}=7,8$

$\Rightarrow x=\left(\sqrt{7,8}\right)^2$

c) $\dfrac{5}{12}\sqrt{x}-\dfrac{1}{6}=\dfrac{1}{3}$

$\Rightarrow\dfrac{5}{12}\sqrt{x}=\dfrac{1}{2}$

$\Rightarrow\sqrt{x}=1,2$

$\Rightarrow x=\left(\sqrt{1,2}\right)^2$

d) $4x^2-1=0$

$\Rightarrow\left(2x-1\right)\left(2x+1\right)=0$

$\Rightarrow\left[{}\begin{matrix}2x-1=0\Rightarrow x=0,5\2x+1=0\Rightarrow x=-0,5\end{matrix}\right.$

e) $\sqrt{x+1}-2=0$

$\Rightarrow\sqrt{x+1}=2$

$\Rightarrow x+1=1,414$

$\Rightarrow x=0,414$

f) $2x^2+0,82=1$

$\Rightarrow2x^2=0,18$

$\Rightarrow x^2=0,09$

$\Rightarrow x=\pm0,3$

g) Không có kết quảCâu trả lời: a) $7-\sqrt{x}=0$