+ \(72:\left(x-15\right)=8\)

\(x-15=9\)

\(x=24\)

+ \(\dfrac{3}{90}-3x=3\)

\(3\left(\dfrac{1}{90}-x\right)=3\)

\(\dfrac{1}{90}-x=1\)

\(x=\dfrac{1}{90}-1=\dfrac{-89}{90}\)

Lời giải:

$(x-15)-x.13=0$

$x-15-x.13=0$

$(x-x.13)-15=0$

$x(1-13)-15=0$

$x.(-12)-15=0$

$x.(-12)=15$

$x=15:(-12)=\frac{-5}{4}$

4x8x25x30x75=(25x4)x(75x8)x10x3x22x63=100x600x10x3x22x63=100x100x10x6x3x22x63=100000x6x3x22x63

Vay tich tren w co tan cung la 5 chu so 0 (nhan voi 100000 co 5 chu so 0)

a,  \(0,5x-\frac{2}{3}x=\frac{7}{12}\)

=> \(x\left(0,5-\frac{2}{3}\right)=\frac{7}{12}\)

=>\(\frac{-1}{6}x=\frac{7}{12}\)=> \(x=\frac{7}{12}:\frac{-1}{6}=\frac{-7}{2}\)

b,  \(x:\frac{13}{3}=-2,5\)

=>\(x=\left(-2,5\right):\frac{13}{3}=\frac{-7,5}{13}\)

c,   \(5,5x=\frac{13}{15}\)

=>\(x=\frac{13}{15}:5,5=\frac{13}{82,5}\)

d,  \(\left(\frac{3x}{7}+1\right):\left(-4\right)=\frac{-1}{28}\)

=>\(\left(\frac{3x}{7}+1\right)=\frac{-1}{28}:\left(-4\right)=\frac{1}{7}\)

=>\(\frac{3x}{7}=\frac{1}{7}-1=\frac{-6}{7}\)

=>\(3x=-6\)

=> \(x=\left(-6\right):3=-3\)

cực gấpppppp

a, \(\left|x+2\right|-\left|x+7\right|=0\Rightarrow\left|x+2\right|=\left|x+7\right|\Rightarrow\orbr{\begin{cases}x+2=x+7\\x+2=-x-7\end{cases}\Rightarrow\orbr{\begin{cases}0=5\left(loại\right)\\2x=-9\end{cases}\Rightarrow}x=\frac{-9}{2}}\)

b, - Nếu \(2x-1\ge0\Rightarrow x\ge\frac{1}{2}\), ta có: 2x - 1 = 2x - 1 => 2x = 2x (thỏa mãn với mọi x)

- Nếu 2x - 1 < 0 => \(x< \frac{1}{2}\), ta có: 2x - 1 = 1 - 2x => 4x = 2 => x = \(\frac{1}{2}\) (không thỏa mãn điều kiện)

Vậy \(x\ge\frac{1}{2}\)

c,d tương tự b

e, tương tự a