Đáp án đúng là:

a ) Đ

b ) Đ

c ) Đ

d) S

Đáp số đúng là:

a) Đ

b) Đ

c) Đ

d) S

ta có \(\frac{8^{10}}{4^8}=\frac{4^{10}.2^{10}}{4^8}=4^2.2^{10}=2^{14}=16384\)

8¹⁰:4⁸=(2³)¹⁰  :  (2²)⁸

=2³⁰:2¹⁶

=2^30-16=2¹⁴

Với x=2 ta có \(f\left(2\right)-3f\left(\frac{1}{2}\right)=4\left(1\right)\)

Với x=1/2 ta có:\(f\left(\frac{1}{2}\right)-3f\left(2\right)=\frac{1}{4}\Rightarrow3f\left(\frac{1}{2}\right)-9f\left(2\right)=\frac{3}{4}\left(2\right)\)

Lấy (1) cộng (2) ta có

\(\Rightarrow f\left(2\right)-3f\left(\frac{1}{2}\right)+3f\left(\frac{1}{2}\right)-9f\left(2\right)=4+\frac{3}{4}\)

\(\Rightarrow-8f\left(2\right)=\frac{19}{4}\)

\(\Rightarrow f\left(2\right)=-\frac{19}{32}\)

\(f\left(\frac{1}{3}\right)+2f\left(\frac{1}{\frac{1}{3}}\right)=\left(\frac{1}{3}\right)^2\Rightarrow f\left(\frac{1}{3}\right)+2f\left(3\right)=\frac{1}{9}\)(1)

\(f\left(3\right)+2f\left(\frac{1}{3}\right)=3^2\Rightarrow2f\left(3\right)+4f\left(\frac{1}{3}\right)=18\)(2)

Từ (1) và (2) \(\Rightarrow2f\left(3\right)+4f\left(\frac{1}{3}\right)-f\left(\frac{1}{3}\right)-2f\left(3\right)=18-\frac{1}{9}\)

\(\Rightarrow3f\left(\frac{1}{3}\right)=\frac{161}{9}\Rightarrow f\left(\frac{1}{3}\right)=\frac{161}{27}\)

giúp vs cả nhà ơi

Ta có: f(x)+3f(1/x)=x^2

với x=2 ta có:

\(f\left(3\right)+3f\left(\frac{1}{2}\right)=4\)(1)

với x=1/2 ta có:

\(f\left(\frac{1}{2}\right)+3f\left(2\right)=\frac{1}{4}\)(2)

=> \(f\left(\frac{1}{2}\right)=\frac{1}{4}-3f\left(2\right)\)

lấy (1) trừ 2 , ta được:

a\(\left[f\left(2\right)+3f\left(\frac{1}{2}\right)\right]-\left[f\left(\frac{1}{2}\right)+3f\left(2\right)\right]=4-\frac{1}{4}\)

=>\(f\left(2\right)+3f\left(\frac{1}{2}\right)-f\left(\frac{1}{2}\right)-3f\left(2\right)=\frac{15}{4}\)

=>\(2f\left(\frac{1}{2}\right)-2f\left(2\right)=\frac{15}{4}\)

=>\(2\left[f\left(\frac{1}{2}\right)-f\left(2\right)\right]=\frac{15}{4}\)

=> \(f\left(\frac{1}{2}\right)-f\left(2\right)=\frac{15}{8}\)

mà \(f\left(\frac{1}{2}\right)=\frac{1}{4}-3f\left(2\right)\)

=>\(\frac{1}{4}-3f\left(2\right)-f\left(2\right)=\frac{15}{8}\)

=>\(-4f\left(2\right)=-\frac{17}{8}\)

=> \(f\left(2\right)=-\frac{17}{32}\)

vậy...

thang cho