Răspuns:
3)
3a-3b=30
3(a-b)=30
a-b=10
7(a-b)=70
a-b=10
a-b-10=0
4) La cate grede Fahrenheit fierbe apa ?
R: 212
6)
E1: x+2y=5
E2: y-4z=7
3*E2: 3y-12z=21
E1+3E2: x+2y+3y-12z=5+21
x+5y-12z=26
7)
a+b=rad 2
a=rad 2-b
b+c=rad 18
c=rad 18-b
c+a=rad 72
rad 2-b+rad 18-b=rad 72
(daca descompunem pe 18 si 72, vom obtine)
rad 2-b+3rad 2-b=6rad 2
4rad 2 -2*b = 6rad 2
2*b=-2rad 2
b=-rad 2
a=rad 2-b
a=2rad 2
c=rad 18-b
c=3rad 2 +rad 2
c=4rad 2
Explicație pas cu pas:
