$\frac{2*4+2*4*8+4*8*16+8*16*32+16*32*64}{3*4+2*6*8+4*12*16+8*24*32+16*48*64}$

0 bình luận về “$\frac{2*4+2*4*8+4*8*16+8*16*32+16*32*64}{3*4+2*6*8+4*12*16+8*24*32+16*48*64}$”

1. Đặt B= 2×4+2x4x8+4x8x16+8x16x32+16x32x64

   = 2x4x(1+8+2x8x16+4x4x32+8x8x64)

   Đặt C=3x4+2x6x8+4x12x16+8x24x32+16x48x64

   =3×4(1+8+2x8x16+4x4x32+8x8x64)

   ⇒B/C=2x4x(1+8+2x8x16+4x4x32+8x8x64)/3×4(1+8+2x8x16+4x4x32+8x8x64)

   =2×4/3×4

   =2/3

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