Theo đầu bài ta có:
\(\frac{1}{5}\cdot a+2+\frac{1}{2}\cdot a+7=a\)
\(\Rightarrow2+7=a-\frac{1}{2}\cdot a-\frac{1}{5}\cdot a\)
\(\Rightarrow a\cdot\frac{3}{10}=9\)
\(\Rightarrow a=30\)

\(\frac{1}{5}a+2+\frac{1}{2}a+7=a\left(\frac{1}{5}+\frac{1}{2}\right)+2+7=\frac{7}{10}a+10=\frac{7a}{10}+10\)

Taco:VD:2.3.4.5>24=>x<0

x=-2=>tổng=0

Vayx=-1

\(\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)=24\)

\(\Leftrightarrow\left(x+1\right)\left(x+6\right)\left(x^2+7x+16\right)=0\)

ko có đáp án nhé . mk nói thật luôn . nếu sai bạn đừng k nhé !

X = 2,340847617

Bằng 2 :v

1+1=2, câu quá dễ, ko phải ko biết làm mà là cố ý

1+1=2

TL :

= 1 054 145 nha bạn

HT

thanks ban

ket ban voi minh di

dễ mà bạn

a)3x-18=0                     à mà mik chx hc phương trình 

3x=18+0                          sorry bạn nhé

3x=18

x=18:3

x=6

vậy x=6

a)\(3x-18=0\)

\(\Leftrightarrow3x=18\)

\(\Leftrightarrow x=6\)

Vậy x=6

b)\(2x.\left(x-4\right)-3x+12=0\)

\(\Leftrightarrow2x.\left(x-4\right)-3\left(x-4\right)=0\)

\(\Leftrightarrow\left(2x-3\right).\left(x-4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}2x-3=0\\x-4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{2}\\x=4\end{cases}}}\)

Vậy .......

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

\(\Leftrightarrow6.\left(\frac{x-1}{2}-\frac{x+3}{3}\right)=6.\left(x+1\right)\)

\(\Leftrightarrow3.\left(x-1\right)-2.\left(x+3\right)=6x+6\)

\(\Leftrightarrow3x-3-2x-6=6x+6\)

\(\Leftrightarrow3x-2x-6x=6+3+6\)

\(\Leftrightarrow-5x=15\)

\(\Leftrightarrow x=-3\)

Vậy x= -3

d)\(\frac{x-3}{x+3}-\frac{5}{3-x}=\frac{30}{x^2-9}\)

\(\Leftrightarrow\frac{x-3}{x+3}-\frac{-5}{x-3}=\frac{30}{\left(x+3\right).\left(x-3\right)}\)

\(\Leftrightarrow\frac{\left(x-3\right).\left(x-3\right)}{\left(x+3\right).\left(x-3\right)}-\frac{-5.\left(x+3\right)}{\left(x-3\right).\left(x+3\right)}=\frac{30}{\left(x-3\right).\left(x+3\right)}\)

\(\Leftrightarrow\left(x-3\right)^2-\left(-5\right).\left(x+3\right)=30\)

\(\Leftrightarrow x^2-6x+9-\left(-5x-15\right)=30\)

\(\Leftrightarrow x^2-6x+9+5x+15-30=0\)

\(\Leftrightarrow x^2-x-6=0\)

\(\Leftrightarrow x^2-3x+2x-6=0\)

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

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

\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=3\end{cases}}}\)

Vậy......

Câu d)

ĐKXĐ:\(x\ne\pm3\)

Cái x=3 loại

Lấy cái x=-2