Question

va rog sa ma ajutati cu exercitiile 20 si 21

Answer 1

20)
a) E(x) nu are valoare definita pentru   :
x-2=0  x=2  
x+2=0  x=-2
b)E(x)=[1+1/(x-2)-2/(x+2)]:1/(x²-4)-x²+5x=
=(x²-4+x+2-2x+4)/(x-2)(x+2) × (x-2)(x+2) -x²+5x=
=x²-x+2 -x²+5x=
=4x+2=
=2(2x+1)
c)E(13)=2(2×13+1)=2×27=54

21)
a) E(x) nu are valoare definita pentru   :
x-1=0  x=1  
x+1=0  x=-1
b)E(x)=7-2×(x+1)/(x-1)×[1/(x-1)-1/(x+1)]:(x-1)⁻²=
=7-2×(x+1)/(x-1)×(x+1-x+1)/(x-1)(x+1): 1/(x-1)²=
=7-4/(x-1)²×(x-1)²=
=7-4/(x-1)²×(x-1)²=
=7-4=3