數學問題(代數)10分 要驗算

4b. 3/4s=-21
4s=3/-21
s=-7/4
驗算: 3/ ( 4 * (-7/4) )
=3*-7
=-21
5a. c/15=3/-5
c=(3/-5) *15
c=(3/-1) *3
c=-9
驗算: -9/15
=-3/5
=3/-5
5b.4/7d=2/5
7d=4/(2/5)
7d=4* (5/2)
d=10/7
驗算: 4/ (7 * (10/7) )
=4/10
=2/5
6a.d/4=6/5
d=(6/5) *4
d=24/5
驗算:(24/5) /4
=(24/5) * (1/4)
=24/20
=6/5
6b.2/3y=-9/4
3y=2/ (-9/4)
3y=2 * (4/-9)
3y= -8/9
y= ( -8/9 ) /3
y= ( -8/9 ) * (1/3)
y= -8/27
驗算:2/ 3*(-8/27)
= 2/ (-8/9)
= 2 * (9/-8)
= -9/4

4b. 3/4s=-21
4s=3/-21
s=-7/4
驗算: 3/ ( 4 * (-7/4) )

=3*-7
=-21
5a. c/15=3/-5
c=(3/-5) *15
c=(3/-1) *3
c=-9
驗算: -9/15

=-3/5
=3/-5
5b.4/7d=2/5
7d=4/(2/5)
7d=4* (5/2)
d=10/7
驗算: 4/ (7 * (10/7) )

=4/10
=2/5
6a.d/4=6/5
d=(6/5) *4
d=24/5
驗算:(24/5) /4

=(24/5) * (1/4)
=24/20
=6/5
6b.2/3y=-9/4
3y=2/ (-9/4)
3y=2 * (4/-9)
3y= -8/9
y= ( -8/9 ) /3
y= ( -8/9 ) * (1/3)
y= -8/27
驗算:2/ 3*(-8/27)

= 2/ (-8/9)
= 2 * (9/-8)
= -9/4

4b. 3/4s = -21
3/4 = -21s
0.75 = -24s
s = -28
5a. c/15 = 3/-5
c = -9
5b. 4/7d = 2/5
4/7d = 0.4
4 = 2.8d
d = 0.7
6a. d/4 = 6/5
d = 4.8
6b. 2/3y = -9/4
2 = -27y/4
8 = -27y
y = 3.375