1)(x-1)/x=3
x-1=3x
x-3x=1
-2x=1
x= -1/2
(x-1)/x=3 |²
(x-1)²/x²=9
(x²-2x+1)/x²=9
(x²-2* (-1/2) +1)/x²=9
(x²+1+1)/x²=9
(x²+1)/x² -1/x²=9
(x²+1)/x² -1/(-1/2)=9
(x²+1)/x² -1/1 * ( -2/1)=9
(x²+1)/x² +2=9
(x²+1)/x²=9-2
(x²+1)/x²=7
p% din (x²+1)/x² = 300 <=> p/100 *7=300 <=> p/100=300/7
p=100*300/7= 30000/7= 4285,7%
2)a+b+c=4 |²
(a+b+c)²=16
a²+b²+c²+2ab+2ac+2bc=16
a²+b²+c²+2(ab+ac+bc)=16
a²+b²+c²+2*5=16
a²+b²+c²+10=16
a²+b²+c²=16-10
a²+b²+c²=6