Find three arithmetic means between -2 and 12.
\(a_1=-2;\ a_2;\ a_3;\ a_4;\ a_5=12\\\\a_5-a_1=4d\\\\4d=12-(-2)\\4d=14\ \ \ /:4\\d=3.5\\\\a_2=a_1+d\to a_2=-2+3.5=1.5\\\\a_3=a_2+d\to a_3=1.5+3.5=5\\\\a_4=a_3+d\to a_4=5+3.5=8.5\\\\Solutions:1.5;\ 5\ and\ 8.5\)