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50 p!!! Rapid, matematica cls a 6-a!!!! (EX 11)

50 P Rapid Matematica Cls A 6a EX 11 class=

Răspuns :

a)9x-18=-63

9x=-63+18

9x=-45

x=-5€Z

b)5x+15=10x-10

15+10=10x-5x

25=5x

x=5€Z

c)8x+2=10x-14

2+14=10x-8x

16=2x

x=8€Z

d)-2x+10=-24x-16+56

24x-2x=40-10

22x=30

x=30/22

x=15/11 nu apartine Z

=> nu are solutii in Z

e)1-4*(-5x+10)=21

1+20x-40=21

20x=21+40-1

20x=60

x=3€Z

f)5x-10-7x-21+35=0

-2x+4=0

-2x=-4

x=2€Z

g)x^2-4x-21=0

delta=16+84

delta=100

=> x1=(4+10)/2=7€Z

x2=(4-10)/2=-3€Z

h)-2x^2+18=0

-x^2+9=0

9-x^2=0

(3-x)(3+x)=0

x1=3€Z

x2=-3€Z