Question

so sánh

A=\(\frac{19^{20}+5}{19^{20}-8}\)và B=\(\frac{19^{21}+6}{19^{21}-7}\)

Answer 1

Ta có:

\(A=\frac{19^{20}+5}{19^{20}-8}=\frac{19^{20}-8+13}{19^{20}-8}=1+\frac{13}{19^{20}-8}\)

\(B=\frac{19^{21}+6}{19^{21}-7}=\frac{19^{21}-7+13}{19^{21}-7}=1+\frac{13}{19^{21}-7}\)

Vì \(19^{20}-8< 19^{21}-7\Rightarrow\frac{13}{19^{20}-8}>\frac{13}{19^{21}-7}\)

\(\Rightarrow A>B\)

Answer 2

A =B NHA ! maivananh

ĐỀU = 1 CẢ . 

Answer 3

Ta có : \(A=\frac{19^{20}+5}{19^{20}-8}=\frac{19^{20}-8+13}{19^{20}-8}=\frac{19^{20}-8}{19^{20}-8}+\frac{13}{19^{20}-8}=1+\frac{13}{19^{20}-8}\)

          \(B=\frac{19^{21}+6}{19^{21}-7}=\frac{19^{21}-7+13}{19^{21}-7}=\frac{19^{21}-7}{19^{21}-1}+\frac{13}{19^{21}-7}=1+\frac{13}{19^{21}-7}\)

Mà : \(\frac{13}{19^{20}-8}< \frac{13}{19^{21}-7}\)

Nên : \(A< B\)

Answer 4

\(A=\frac{19^{20}-8+13}{19^{20}-8}=\frac{13}{19^{20}-8}\)+1

\(B=\frac{19^{21}-7+13}{19^{21}-7}=\frac{13}{19^{21}-7}+1\)

Suy ra A>B