Question

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Answer 1

Explicație pas cu pas:

Ex.2

a)1,5+x=-7,5

x=-7,5-1,5

x=-9

b) 11/4+y=3

y=3-11/4

y=1/4

c) z+0,(3)=2/3

z+3/9=2/3

z+1/3=2/3

z=2/3-1/3

z=1/3

d) y-5/6=1/2

y=1/2+5/6

y=4/3

e) -7/2×x=0,5

x=-2/7×0,5

x=-2/7×1/2

x=-1/7

f) a-0,2(3)=4/15

a-21/90=4/15

a-7/30=4/15

a=4/15+7/30

a=1/2

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Ex.3

a) -0,5x=-7,5

x=15

b) -5/2y=1/4

-2/5×(-5/2)y=2/5×1/4

y=-1/5×1/2

y=-1/10

c) 1,4z=-7/2

1,4z:1,4=-7/2:1,4

z=-7/2:7/5

z=-7/2×5/7

z=-1/2×5

z=-5/2

d) 6/5u=0,8

u=5/6×0,8

u=5/6×4/5

u=1/3×2

u=2/3

e)9,9:x=-3

99/10×1/x=-3

99/10x=-3

99=-30x

-30x=99

x=-33/10

f) x:(-6/7)=13/6

-x×7/6=13/6

-7/6x=13/6

x=-13/7

g) -1,6:x=0,8

-8/5×1/x=0,8

-8/5x=0,8

-8=4x

4x=-8

x=-8:4

x=-2

h) y:5/2=3,4

y×2/5=3,4

2/5y=3,4

y=5/2×3,4

y=5/2×17/5

y=1/2×17

y=17/2