15 mũ 3 + 5 x 15 mũ 2 -5 mũ 3

= 3375 + 5 x 225 - 125

= 3375 + 1125 -125

= 4500 - 125

= 4375

ddddddd

\(15^3+5.15^2-5^3.\frac{1}{8}^3+6.18^2-6^3\)

\(=15^2.\left(15+5\right)-\left(5.\frac{1}{8}\right)^3+6.\left(18^2-6^2\right)\)

\(=225.20-\left(\frac{5}{8}\right)^3+6.\left(324-36\right)\)

\(=4500-\frac{125}{512}+6.288\)

\(=\left(4500+1728\right)-\frac{125}{512}\)

\(=6228-\frac{125}{512}\)

\(=...........\)

15^3+5.15^2-5^3 / 18^3+6.18^2-6^3

=3375+5.225-125 /5832+6.324-216

=3375+1125-125 /5832+1944-216

=4500-125 /7826-216

=4375 /7610

=875 /1522

mk ko bt viết phần nên viết phần bằng dấu gạch / nhé.mk cx ko bt đúng hay sai đâu nhé

\(\dfrac{15^3+5.15^2-5^3}{18^3+6.18^2-6^3}\)

= \(\dfrac{\left(5.3\right)^3+5.\left(5.3\right)^2-5^3}{\left(6.3\right)^3+6.\left(6.3\right)^2-6^3}\)

= \(\dfrac{5^3.3^3+5^3.3^2-5^3}{6^3.3^3+6^3.3^2-6^3}\)

= \(\dfrac{5^3.\left(3^3+3^2-1\right)}{6^3.\left(3^3+3^2-1\right)}\)

=\(\dfrac{5^3}{6^3}=\dfrac{125}{216}\)

Gọi giá trị trên là : A

\(A=3^{100}-3^{99}+3^{98}+....+3^2-3+1\)

\(\Rightarrow3A=3^{101}-3^{100}+3^{99}-3^{98}+......+3^3-3^2+3\)

\(\Rightarrow3A+A=3^{101}+1\)

\(\Rightarrow4A=3^{101}+1\Rightarrow A=\frac{3^{101}+1}{4}\)

3³×5³+5×3²×5²-5³/ 6³+3³+ 6×6²×3²-6³=5³×(3³+3²- 1)/6³×(3³+3²-1)=5³/6³⁼125/216