Question

[GOT7 JACKSON]

NHANH VÀ ĐÚNG , TRÌNH BÀY ĐẦY ĐỦ = TICK NHA

B1 : Tìm x :

a. \(3.\left(2x-\dfrac{1}{2}\right)+2.\left(\dfrac{3}{8}-x\right)=2,75\)

b. \(x-\dfrac{1}{3}.\left(5-3x\right)=1\dfrac{1}{2}x+5\dfrac{1}{2}\)

c. \(\sqrt{x-1}=4\)

d. \(\left|x\right|-5\dfrac{3}{7}.\left|-x\right|-\dfrac{3}{4}=2.\left|x\right|-1\dfrac{1}{7}\)

e. \(x^2=8.\sqrt{x}\)(với x ≥ 0)

g) 3^x+2 + 3^x = 810

Answer 1

[Akai Haruma]

a)

\(3(2x-\frac{1}{2})+2(\frac{3}{8}-x)=2,75\)

\(\Leftrightarrow 6x-\frac{3}{2}+\frac{3}{4}-2x=2,75\)

\(\Leftrightarrow 4x=\frac{7}{2}\Rightarrow x=\frac{7}{8}\)

b)

\(x-\frac{1}{3}(5-3x)=1\frac{1}{2}x+5\frac{1}{2}\)

\(\Leftrightarrow x-\frac{5}{3}+x=x+\frac{1}{2}x+\frac{11}{2}\)

\(\Leftrightarrow \frac{1}{2}x=\frac{43}{6}\) \(\Rightarrow x=\frac{43}{3}\)

Answer 2

[Akai Haruma]

c) \(\sqrt{x-1}=4\Rightarrow x-1=4^2\Rightarrow x=4^2+1=17\)

d)

\(|x|-5\frac{3}{7}|-x|-\frac{3}{4}=2|x|-1\frac{1}{7}\)

\(\Leftrightarrow |x|-\frac{38}{7}|x|-\frac{3}{4}=2|x|-\frac{8}{7}\)

\(\Leftrightarrow |x|(1-\frac{38}{7}-2)=\frac{3}{4}-\frac{8}{7}\)

\(\Leftrightarrow |x|.\frac{-45}{7}=\frac{-11}{28}\)

\(\Leftrightarrow |x|=\frac{11}{180}\Rightarrow \left[\begin{matrix} x=\frac{11}{180}\\ x=-\frac{11}{180}\end{matrix}\right.\)