(有向數) 20分 今日要 + 算草【】

你好～～～

以下都是本人的一些意見而已，如有錯誤請多多指教～～

6A.(-54)÷(+2)÷(-3)

= (-27) ÷ (-3)

= [(-1) ÷ (-1)] x [(+27) ÷ (+3)]

= +9

= 9

6B.(-56)÷(-4)x(+7)

= (+14) x (+7)

= 14 x 7

= 98

6C.(256)÷(+16)÷(-2)÷(-8)

= 16 ÷ (-2) ÷ (-8)

= (-8) ÷ (-8)

= +1

6D.(-32)(+3)÷(-24)(-2)

= (-96) ÷ (+48)

= -2

8A.(-8)x(+6)÷【(+8)-(+5)】

= (-48) ÷ (8 - 5)

= (-48) ÷ (+3)

= -16

8B.(+11)-(-2)x【(+6)÷(-3)+(-2)】

= (+11) - (-2) x [(-2) - 2]

= (+11) - (-2) x (-4)

= +11 - (+8)

= 11 - 8

= 3

8D.【(-5)(-2)-(+3)(+4)】÷【(-6)+(-4)】x(+2)

= [(+10) - (+12)] ÷ [(-6) - 4] x (+2)

= (10 - 12) ÷ (-10) x (+2)

= (-2) ÷ (-10) x (+2)

= 2 ÷ 10 x 2

= 4 ÷ 10

= 4 / 10

= 2 / 5

要記得一些做這些題目的原則︰

１）(-x) ÷ (-y) = [(-1) ÷ (-1)](x ÷ y) = (+1)(x ÷ y) = x ÷ y

２）(-y) x (-z) = [(-1) x (-1)](y x z) = (+1)(y x z) = y x z

３）(-y) ÷ (+z) = (-1)(y ÷ z)

４）(+y) ÷ (-z) = (-1)(y ÷ z)

５）(-y) x (+z) = (-1)(y x z) = -yz

６）(+y) x (-z) = (-1) x (+y) x (+z) = -yz

７）(+y) - (-z) = (+y) + z = y+ z

８）(-y) + (+z) = (+z) + (-y) = z - y

等等……

希望可以幫到你～～～～～