Question

5 mũ 20 - 5 mũ 15 / 5 mũ 16 + 5 mũ 18

Answer 1

\(\dfrac{5^{20}-5^{15}}{5^{16}+5^{18}}\)

\(=\dfrac{5^{15}\cdot\left(5^5-1\right)}{5^{16}\cdot\left(1+5^2\right)}\)

\(=\dfrac{3125-1}{5\cdot\left(1+25\right)}\)

\(=\dfrac{3124}{5\cdot26}\)

\(=\dfrac{1562}{65}\)

Answer 2

\(\dfrac{5^{20}-5^{15}}{5^{16}+5^{18}}\\ =\dfrac{5^{15}\left(5^5-1\right)}{5^{16}\left(1+5^2\right)}\\ =\dfrac{5^5-1}{5\left(1+25\right)}\\ =\dfrac{3125-1}{5\cdot26}\\ =\dfrac{3124}{130}\\ =\dfrac{1562}{65}\)