Question

7: [a x (4+8) : 2]+3=4 ; [14-(6:a+4)xa]:4=1 ; 5-[ a+6x(a:2+3)]:10=0 ; [8+(15-a):a]:5=2 ; va rog este urgent multumesc

Answer 1

7: [a x (4+8) : 2]+3=4
7: (a x 12 : 2)+3=4
7: (a x 6)+3=4
7: (a x 6)=4-3
7: (a x 6)=1
ax6=7
a=7:6
a = 1,1(6)

 [14-(6:a+4)xa]:4=1
[14-(6:a+4)xa]=4
14-(6:a+4)xa=4
-(6:a+4)xa = -10
(6:a+4)xa=10
(6:a+4) = 10a
6+4a=10a²
3+2a=5a²
5a²-2a-3=0
Δ=4+60=64
a1 = (2-8)/10=-6/10=-3/5
a2= (2+8)/10=1

5-[ a+6x(a:2+3)]:10=0
[ a+6x(a:2+3)]:10=5
[ a+6x(a:2+3)]=50
a+6(a/2+3)=50
a+6a/2+18=50
a+3a+18=50
4a=50-18
4a=32
a=8

[8+(15-a):a]:5=2
8+(15-a):a=10
(15-a):a=10-8
(15-a):a=2
15-a=2a
3a=15
a=15:3
a=5