1) (а-2)/2
а=1 (1-2)÷1=-1
а=2 1/2 (2 1/2-2)÷2 1/2=2÷(2 1/2)=(1/2)*2/5=1/5
а=0,4 (0,4-2)÷0,4=-1,6÷0,4=-4
а=0,5 (0,5-2)÷0,5=-1,5÷0,5=-3
2) (m+12)/(3m-4)
m=0.5 (0,5+12)÷(3*0,5-4)=12,5÷(-2,5)=-5
m=2 (2+12)÷(3*2-4)=14/2=7
m=1/3 (1/3+12) ÷(3*1/3-4)=(12 1/3)÷(-3)=37/3*(-1/3)=-37/9=-4 1/9
m=-2/3 (-2/3+12)÷(-2/3*3-4)=(11 1/3)÷(-6)=(11 1/3)*(-1/6)=34/3*(-1/6)=-34/18=-17/9=-1 8/9
3) 2b/(1-b²)
b=1/2 ( 1/2*2)÷(1-(1/2)²)=1÷(1-1/4)=1÷(3/4)=1*4/3=4/3=1 1/3
b=1 2*1÷(1-1²)=2÷0 =∞
b=-1 2*(-1)÷(1-(-1)²)=-2÷0= -∞
b=0 2*0÷(1-0²)=0
4) (y+2) /(y²-2)
y=0 (0+2)÷(0²-2)=2÷(-2)=-1
y=-2 ( -2+2)÷((-2)²-2)=0÷(-2)=0
y=2 (2+2)÷(2²-2)=4÷2=2
y=4 (4+2)÷(4²-2)=6÷6=1