Question

Tìm x : 

a) 2x + 5 - ( x - 7 ) = 18

b) 2 ( x + 1 ) + \(^{4^2}\) = \(^{2^4}\)

c) \(\frac{X-3}{X+5}\). =  \(\frac{5}{7}\)

Answer 1

a) \(2x+5-\left(x-7\right)=18\)

\(2x+5-x+7=18\)

\(x+12=18\)

\(x=18-12\)

\(x=6\)

b) \(2\left(x+1\right)+4^2=2^4\)

\(2\left(x+1\right)+16=16\)

\(2\left(x+1\right)=16-16\)

\(2\left(x+1\right)=0\)

\(\Rightarrow\left(x+1\right)=0\)

\(x=0-1\)

\(x=-1\)

 

c) \(\frac{x-3}{x+5}=\frac{5}{7}\)

\(\Rightarrow\left(x-3\right)7=\left(x+5\right)5\)

\(7x-21=5x+25\)

\(7x-5x=25+21\)

\(2x=46\)

\(x=\frac{46}{2}\)

\(x=23\)

Answer 2

Answer 3

a/2x+5-(x-7)=18

2x-x+5+7=18

x=18-5-7=6

b/2x+2+4^2=2^4

2x+2+16=16

2x+2=0

2x=-2

x=-1

Answer 4

a) x=6

b) x=-1

c)x=23