Question

Tính nhanh :

A = \(\frac{1x5x6+2x10x12+4x20x24+9x45x54}{1x3x5+2x6x10+4x12x20+9x7x45}\)

Answer 1

Ta có:

\(A=\frac{1x5x6+2x10x12+4x20x24+9x45x54}{1x3x5+2x6x10+4x12x20+9x27x45}\)

\(=\frac{1x3x5x2+2x6x10x2+4x12x20x2+9x27x45x2}{1x3x5+2x6x10+4x12x20+9x27x45}\)

\(=\frac{\left(x3x5+2x6x10+4x12x20+9x27x45\right)x2}{x3x5+2x6x10+4x12x20+9x27x45}\)

\(=2\)

Answer 2

\(A=\frac{1x5x6+1.2x2.5x2.6+1.4x4.5x6.4+1.9x5.9x6.9}{1x3x5+1.2x3.2x2.5+1.4x3.4x5.4+1.7x3.3x5.9}\)

\(A=\frac{1x5x6\left(1+2.2.2+4.4.4+9.9.9\right)}{1x3x5\left(1+2.2.2+4.4.4+7.3.9\right)}\)

\(A=\frac{1x5x6.802}{1x3x5.262}\)\(A=\frac{1x5x6.2.401}{1x3x5.2.131}\)

còn đâu cậu tự làm