Question

dau coroana +40 de puncte.
VA ROG!!

Answer 1

a)
2/3 + 1/6 +5/18 = 
→ cmmmc al numerelor ( 3, 6, 18) = 18 
→ amplific prima fractie cu 6, a doua fractie cu 3 

= ( 2 x 6)/ 18 + 3/18 + 5/18 =
= 12/18 + 3/18 + 5/18 =
= 20/18=
= 10/9=
= 1 intreg si 1/9=
= 1,(1)

b)
4/5 + 2/15 - 1/30 =
→ cmmmc al numerelor( 5,15,30) = 30
→amplific fractiile cu 6, respectiv cu 2

= (4 x 6 ) /30 + ( 2 x 2)/30 - 1/30 = 24/30 + 4/30 - 1/30 = 28/30 - 1/30 = 
= 27/30 = 9/10

c)  3/5 + 1/2 + 5/7 = (3 x 14 ) /70 + 35/70 + (10 x 5 )/70 =
= 42/70 +  35/70  +  50/70=
= 127/70
→ cmmmc al numerelor( 5, 2,  7) = 70
→ amplific fractiile pentru a obtine acelasi numitor comun

d) 1/4 + 2/5 + 7/9 =45/180 + 72/180 + 140/180 = 257/80=1,42(7)
→ cmmmc al numerelor ( 4, 5, 9) = 180
→ amplific fractiile cu 45 prima fractie, cu 36 a doua fractie si cu 20

e)  ( 5/12 + 3/10 - 1/6) : 5/24 =        →cmmmc ( 12, 10,16) = 60
= ( 25/60 + 18/60  - 10/60) : 5/24=   →amplific fractiile
= ( 43/60 - 10/60) : 5/24 =
=33/60  × 24/5=
=11/20 × 24/5 =
= 66/25=
= 2 intregi si 16/25 


f)  ( 2/9 + 1/12 + 13/30) :5/90=
= ( 40/180 + 15/180 + 78/180) :5/90=
= 133/180  × 90/50 =
= 133/( 2x50) = 
= 133/100
= 1,33

→cmmmc al numerelor ( 9, 12, 30) = 180
→ amplific fractiile cu 20, cu 15, si cu 6

g)  1/2 × (1/3 + 1/6) = 1/2 × ( 2/6 + 1/6)  = 1/2 × 3/6 = 3/12 = 1/4

h)  1/6 + 3/2 × ( 3/4 - 2/4) = 1/6 + 3/2 × 1/4 = 1/6 + 3/8 =
= 4/24 +  9/24 = 13/24

i)   7/3 : ( 3/2 - 1/3 ) = 7/3 : ( 9/6 - 2/6) = 7/3 : 7/6 = 7/3 × 6/7 = 2