Am nevoie urgent de rezolvari!
1. x²+(y+1)=0 , x+y=?
2. 0,5+7*1/5=?
3. Daca a/b=3/8 , aflati:
a) Ce procent reprezinta a din b
b) Valoarea raportului a²+b²/2ab
4. Determinati elementele multimii : A={ x apartine numerelor intregi | 17/x-2 apartine numerelor intregi}
5. Opt muncitori ar executa o lucrare in 6 zile. Doi muncitori se imbolnavesc la trei zile dupa ce a inceput lucrarea. In cate zile este finalizata lucrarea?
Multumesc mult!

1

Răspunsuri

Cel mai inteligent răspuns!
2014-08-07T01:22:38+03:00
1)x²=0  =>x=0

y+1=0  =>y= -1

x+y= 0-1=-1

2)5/10 + 7/5= (5+14)/10= 19/10=1,9

3)a/b=3/8  =>a=3b/8

a) p% din a=b

p/100  *3b/8= b

p/100 = b/3b/8

p/100= b * 8/3b

p/100= 8/3

p=100*8/3

p=800/3

p=266,6%

b)(a²+b²)/2ab=  [(3b/8)² +b²]/2 *3b/8 *b=

= (9b²/64 +b²) /3b²/4=

= (9b²+64b²)/64/3b²/4=

=73b²/64 * 4/3b²=

=73/16

4) 17/(x-2) ∈Z   =>  (x-2)|17   =>x-2∈{-1,1,-17,17}

1)x-2= -1  =>x= 1

2) x-2=1  =>x= 3

3)x-2= -17  =>x= -15

4) x-2= 17  =>x= 19

x={-15;1;3;19}

5)8m...........1l..........6z
    8m............x...........3z    sunt direct proportionale

x=3*1/6= 1/2

1-1/2=  (2-1)/2=  1/2

8m........1l.........6z
6m.........1/2......y

6/y= 6/8 * 1/1/2

6/y= 6/8 * 2/1

6/y= 3/4 *2

6/y=3/2  =>y= 6*2/3=  2*2=4 zile

3+4=7 zile termina toata lucrarea
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