中一數學功課問題,聽日交(10分!!!!!!!!!!!!!!!!)

第一題：
+13 ÷ -0.5 = (13 ÷ 5 x 10) = -26 <<0.5 = 5 ÷ 10 (÷ ÷ = x) >>
-16 × +0.5 = -16 x 5 ÷ 10 = - 8
[(+13)÷(-0.5)-(-16)×(+0.5)]=-2.6- (- 8) = 8 - 26 = <<<負負得正>>>

0.75 x 4 = 3

[(+13)÷(-0.5)-(-16)×(+0.5)]÷[(0.75)×(-4)]= - 18 ÷ 3 = -6


第二題：


1- 2/3 = 1/3 < 2/3=3分之2 >

-12 × 3/8 = -9/2

[+(1-3分之2)-(-12)×(+8分之3)] = 1/3 - -9/2 = 29/6

29/6 ÷ 1/4 = 58/3 (化簡就=+19又3分之1)

[(+13)÷(-0.5)-(-16)×(+0.5)]÷[(0.75)×(-4)]
= [(13 / -0.5) - (-16 x 0.5)] ÷ (-3)
= [-26 - (-8)] ÷ (-3)
= (-26 + 8) ÷ (-3)
= -18 ÷ (-3)
= 6

[+(1-3分之2)-(-12)×(+8分之3)]÷4分之1
= [(1 - 2/3) - (-12) x (3/8)] ÷ 1/4
= [1/3 - (-4.5)] ÷ 1/4
= (1/3 + 9/2) ÷ 1/4
= 29/6 x 4
= 116/6
= 19 1/3

記住 先乘除, 後加減o我！

[(+13)÷(-0.5)-(-16)×(+0.5)]÷[(0.75)×(-4)]

=(13÷ -0.5)+16×0.5)+ 0.75× -4

= (-18)÷(-3)

= -6