Question

va rog este foarte urgent!​

Answer 1

Răspuns:

9. 1,19

10. 8

11.650

12.a=5

b=7

c=9

13.a=26,b=8

a=8,b=26

Explicație pas cu pas:

9. 1,2²-0,5²=1,44-0,25=1,19

10.b+c=2

1+1=2

a=2

b=1

c=1

(2²)¹ × (2¹)¹

4¹×2¹

4×2=8

11. 2+4+.......+50

N=(50-2):2+1

N=48:2+1

N=24+1

N=25

S=(50+2)×25:2

S=52×25:2

S=26×25

S=650

12. (a+b+c):3=7

b=a+1

c=a+2

(a+b+c):3=7/×3

a+b+c=21

a+a+1+a+2=21

3a=19=>rezulta ca numerele a b c sunt consecutive pare

b=a+2

c=a+4

a+b+c=21

a+a+2+a+4=21

3a+6=21

3a=15

a=5

b=a+2

b=5+2

b=7

c=a+4

c=5+4

c=9

13. primul caz

a-b=18=>a=b+18

a:b=3 rest 2=>a=3b+2

3b+2=b+18/-2

3b=b+16/-b

2b=16

b=8

a=b+18

a=8+18

a=26

al doilea caz

b:a=3 rest 2=>b=3a+2

b-a=18=>b=a+18

3a+2=a+18/-2

3a=a+16/-a

2a=16/:2

a=8

b=a+18

b=8+18

b=26