Question

Tìm x biết;

a) \(\frac{x-4}{2015}\)- \(\frac{1}{2015}\)= \(\frac{10-2x}{2015}\)

b) 2^x  +  2^x+4 = 272

Answer 1

\(2^x+2^{x+4}=272\)

\(< =>2^x.\left(1+2^4\right)=272\)

\(< =>2^x.17=272\)

\(< =>2^x=272:17\)

\(< =>2^x=16\)

\(< =>2^x=2^4\)

\(=>x=4\)

Answer 2

a, x-4/2-15-1/2015=10-2x

qua điều trên:

Ta thấy rằng :

x-5=10-2x

=>

x=15-2x

=>

0=15-3x

=>x=5

Ta có:

2^x+2^x+4=272

=> 2^x.(1+16)=272

=>2^x.17=272

=>2^x=16

=>x=4

Answer 3

\(\frac{x-4}{2015}-\frac{1}{2015}=\frac{10-2x}{2015}\)

\(< =>\frac{x-4-1}{2015}=\frac{10-2x}{2015}\)

\(< =>\frac{x-5}{2015}=\frac{10-2x}{2015}\)

\(< =>\frac{x-5}{2015}-\frac{10-2x}{2015}=0\)

\(< =>\frac{x-5-\left(10-2x\right)}{2015}=0\)

\(< =>\frac{x-5-10+2x}{2015}=0\)

\(< =>\frac{3x-15}{2015}=0\)

\(< =>3x-15=0\)

\(< =>3x=15\)

\(< =>x=5\)