Question

Buna
va rog e urgent

Answer 1

Răspuns:

1. notam   caiete= a carti= b

2a + 3b= 50    3a+ 4b= 69   daca le scadem avem a+b= 19 lei

6a + 8b - 6a -9b =

6a + 9b- 6a - 8b= 150- 138     => b= 150- 138=>  b= 12 lei (1 carte)

2a= 50 - 3 x12= 50-36      2a= 14=> a= 14:2 = 7 lei   a= 7 lei ( 1 caiet)

2.

2x (1+2+3+...+50)= 7650 =>  2x = 7650 : ( 1+2+3+...+50)

1+2+3+...+ 50= 50x51:2= 1275

2x= 7650 :1275     => 2x= 6  x= 6:2 = 3   x= 3

3. a+b+c= 1838 jucarii   ( a, b, c - cele 3 zile)

c= 2a+54    c= b+75   2a+ 54= b+75   2a  =b+75- 54= b+21

b= 2a- 21

a+ 2a- 21 + 2a +54= 1838

5a = 1838+ 21 -54 = 1805     a= 1805 :5 = 361   a= 361 jucarii in prima zi

b= 2x361 - 21 = 701     b= 701 jucarii a doua zi

c= 2 x361+ 54= 776    c= 776 jucarii a treia zi

4. $3^{n} * 5^{n}$ ( 3+ $5^{3}$ - 2 * $3^{2}$) = $3^{n} * 5^{n}$ ( 3 + 125 - 18) = $3^{n} * 5^{n}$ *110

ultima cifra va fi 0  ( exemplu 3 * 5 *110= 1650 , 9 *25* 110=24750)

5. $4^{112}$ ( 1 + 4 + $4^{2}$ + $4^{3}$) = $4^{112}$ ( 5+16 + 64) = $4^{112}$ * 75    : 5 se imparte la 5 exact

6. [ ( b+ 1) x 2 + 3]x4 = p    p:2= 10    p=20

[ ( b+ 1) x 2 + 3]x4= 20

[ ( b+ 1) x 2 + 3] = 20 :4 = 5

(b+1)x 2 = 5-3 = 2

(b+1) x2= 2    b+ 1= 2:2 = 1     b+1= 1 => b=0    0 briose