× ÷ ×0.99
8× + ÷ a× a+ (a≥0)
照这样的规律排列,第5幅图有个●;第n幅图有个●。
× = ÷4= 0× = + × =
7.5× = ÷ = ÷25%= 6×( - )=
① × ÷
② +6÷
③ ÷ ÷
④( -0.25)×2.4
⑤ × +0.625×