\(a,\left[0,75x+\frac{5}{2}\right]-\frac{4}{7}-\left[-\frac{1}{3}\right]=-\frac{5}{6}\)

\(\Leftrightarrow\left[0,75x+\frac{5}{2}\right]-\frac{4}{7}+\frac{1}{3}=-\frac{5}{6}\)

\(\Leftrightarrow\left[0,75x+\frac{5}{2}\right]=-\frac{5}{6}-\frac{1}{3}+\frac{4}{7}\)

\(\Leftrightarrow0,75x+\frac{5}{2}=-\frac{25}{42}\)

\(\Leftrightarrow0,75x=-\frac{65}{21}\Leftrightarrow x=-\frac{260}{63}\)

\(b,\left[4x-9\right]\left[2,5+-\frac{7}{3}x\right]=0\)

\(\Leftrightarrow\orbr{\begin{cases}4x-9=0\\2,5+-\frac{7}{3}x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{9}{4}\\x=\frac{15}{14}\end{cases}}\)

Vậy \(x\in\left\{\frac{9}{4};\frac{15}{14}\right\}\)

Tham khảo nhé phamthiminhanh

ai giúp mình nhanh với nhé! Mình cảm ơn trước

a) x : 2,5 = 1/100

x = 1/250 * 2,5

x= 1/100

b) 5/3= x : 4/5

x= 4/5 * 5/3

x= 4/3

a) \(x\div2.5=0.003\div0.75\)

\(x\div2.5=0.004\)

\(x=0.004×2.5\)

\(x=0.01\)

Vậy, \(x=0.01\)

b) \(\frac{2}{3}\div0.4=x\div\frac{4}{5}\)

\(x\div\frac{4}{5}=\frac{5}{3}\)

\(x=\frac{5}{3}×\frac{4}{5}\)

\(x=\frac{20}{15}=\frac{4}{3}\)

Vậy, \(x=\frac{4}{3}\)

Cbht

Bài 1: 25/100 = 0,25 ; 1999/1000 = 1,999

b) 0,75 = 75/100; 2,5 = 25/10

Bài 2 :

Ta có :X = 20012001 + 1999 x 20012001

X = 1999 + 1 x 20012001

X = 2000 x 20012001

Ta có :Y = 20012001 x 2001 - 20012001

Y = 20012001 x 2001 - 1

Y = 20012001 x 2000

Ta thấy :2000 x 20012001 = 20012001 x 2000

Vậy : X = Y

a) Ta có: 36-x=44

nên x=36-44=-8

Vậy: x=-8

b) Ta có: \(\dfrac{5}{6}-x=\dfrac{7}{4}-0.75-3\)

\(\Leftrightarrow\dfrac{5}{6}-x=\dfrac{7}{4}-\dfrac{3}{4}-3=1-3=-2\)

hay \(x=\dfrac{5}{6}+2=\dfrac{17}{6}\)

a) 36-x=44                                  b) 5/6-x=7/4-0,75-3

=> x= 36-44                                => 5/6-x= -2

=> x= -8                                      => x= 5/6-(-2)

                                                    => x=17/6

− 1 4 + x + 0 , 75 = 3 1 2 → x = 7 2 − 3 4 + 1 4 → x = 3

3 . x + 25% . x = -0,75

3 . x + 0,25 . x = -0,75

x . ( 3 + 0,25 ) = -0,75

x . 3,25 = -0,75

x         = -0,75 : 3,25

x          = \(-\frac{3}{13}\)

X*(1/3-0.5)=0.75

X*-1/6=0.75

X=0.75/(-1/6)

X=-9/2

1/3*x-1/2*x=0,75.

(1/3-1/2)*x=3/4.

-1/6*x=3/4.

x=3/4:(-1/6).

x=-9/2.

Vậy x=-9/2.