Đáp án: $2$
Giải thích các bước giải:
Ta có:
$\dfrac{1.5.6+2.10.12+3.15.18+4.20.24+5.25.30}{1.3.5+2.6.10+3.9.15+4.12.20+5.15.25}$
$=\dfrac{1.5.6+2^3.1.5.6+3^3.1.5.6+4^3.1.5.6+5^3.1.5.6}{1.3.5+2^3.1.3.5+3^3.1.3.5+4^3.1.3.5+5^3}$
$=\dfrac{1.5.6(1+2^3+3^3+4^3+5^3)}{1.3.5(1+2^3+3^3+4^3+5^3)}$
$=\dfrac{1.5.6}{1.3.5}$
$=2$
