Question

1)Tính nhanh biểu thức

A=\(\frac{1.5.6+2.10.12+3.15.18+4.20.24+5.25.30}{1.3.5+2.6.10+3.9.15+4.12.20+5.15.25}\)

Answer 1

\(A=\frac{\text{1.5.6 + 2.10.12 + 3.15.18 + 4.20.24 + 5.25.30}}{\text{1.3.5 + 2.6.10 + 3.9.15 + 4.12.20 + 5.15.25 }}\)

\(=\frac{1.5.6+2.\left(1.5.6\right)+3.\left(1.5.6\right)+4.\left(1.5.6\right)+5.\left(1.5.6\right)}{1.3.5+2.\left(1.3.5\right)+3.\left(1.3.5\right)+4.\left(1.3.5\right)+5.\left(1.3.5\right)}\)

\(=\frac{30.\left(1+2+3+4+5\right)}{15.\left(1+2+3+4+5\right)}\)

\(=\frac{30}{15}=2\)

Vậy A=2.

Answer 2

Bấm máy tính