\(2x+x=-3+15+5+30\)

\(3x=47\)

\(x=\frac{47}{3}\)

hình như bạn sai r hay sao ý

Sao ko ai giúp m vậy,huhu

-7/20

-1/6

10/21

\(a,-\dfrac{12}{16}-\left(\dfrac{3}{4}-x\right)=-\dfrac{5}{3}\)

\(\dfrac{3}{4}-x=-\dfrac{12}{16}-\left(-\dfrac{5}{3}\right)\)

\(\dfrac{3}{4}-x=\dfrac{11}{12}\)

\(x=\dfrac{3}{4}-\dfrac{11}{12}\)

\(x=-\dfrac{1}{6}\)

\(b,x-\dfrac{3}{7}:\dfrac{9}{14}=-\dfrac{7}{3}\)

\(x-\dfrac{3}{7}=-\dfrac{7}{3}\times\dfrac{9}{14}\)

\(x-\dfrac{3}{7}=-\dfrac{3}{2}\)

\(x=-\dfrac{3}{2}+\dfrac{3}{7}\)

\(x=-\dfrac{15}{14}\)

\(c,-\dfrac{3}{4}x+\dfrac{5}{8}x=\dfrac{1}{3}\)

\(\left(-\dfrac{3}{4}+\dfrac{5}{8}\right)x=\dfrac{1}{3}\)

\(-\dfrac{1}{8}x=\dfrac{1}{3}\)

\(x=\dfrac{1}{3}:\left(-\dfrac{1}{8}\right)\)

\(x=-\dfrac{8}{3}\)

\(x-\dfrac{1}{4}=\dfrac{5}{3}\times\dfrac{4}{9}\\ \Rightarrow x-\dfrac{1}{4}=\dfrac{20}{27}\\ \Rightarrow x=\dfrac{20}{27}+\dfrac{1}{4}\\ \Rightarrow x=\dfrac{107}{108}\)

=>x-1/4=20/27

hay x=107/108

-15 +40 = 40-15=25

-100-(-100) =100 -100=0

(-5).75+(-5).25=(-5).(75+25)= - 500

3³ +2016^o.(-5) = 27+1.(-5) = 22

tinh nhanh;

(-27)+4²+18+27 = 2(8+9) =34

(-10-20).(-5) = (-30).(-5)    =150

\(a,\left(3x-7\right)\left(x+5\right)=\left(5+x\right)\left(3-2x\right)\)

\(\Leftrightarrow\left(3x-7\right)\left(x+5\right)-\left(x+5\right)\left(3-2x\right)=0\)

\(\Leftrightarrow\left(x+5\right)\left(3x-7-3+2x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+5=0\\5x-10=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)

\(b,\dfrac{-x+3}{2}=\dfrac{x-2}{3}\left(MSC=6\right)\)

Suy ra :

\(3\left(-x+3\right)=2\left(x-2\right)\)

\(\Leftrightarrow-3x+9-2x+4=0\)

\(\Leftrightarrow-5x+13=0\)

\(\Leftrightarrow x=\dfrac{13}{5}\)

\(c,\dfrac{x-1}{x-2}+\dfrac{5}{x+2}=\dfrac{12}{x^2-4}+1\)\(\left(dkxd:x\ne\pm2\right)\)

\(\Leftrightarrow\dfrac{\left(x-1\right)\left(x+2\right)+5\left(x-2\right)-12-x^2+4}{x^2-4}=0\)

\(\Leftrightarrow x^2+2x-x-2+5x-10-12-x^2+4=0\)

\(\Leftrightarrow6x-20=0\)

\(\Leftrightarrow x=\dfrac{10}{3}\)\(\left(n\right)\)

Vậy \(S=\left\{\dfrac{10}{3}\right\}\)

a
b

phải ko bn

=> 5.x = 900-180 = 6=720

=> x = 720 : 5 = 144

k mk nha

Bài này bình thôi, bạn chỉ cần làm như này thôi này:

5.x=900 - 180

<=> 5.x = 720

<=> x = 720 : 5

<=> x = 144

Vậy x = 144