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Verified answer

a) E(x)=4x²+12x+9-2x-x²+6+3x-x²-4x-4-x²-7x-10

E(x)=x²+2x+1

E(x)=(x+1)², pentru orice x număr real

b) (a²+1)²-(-a²+1)²=16

[a²+1-(-a²+1)]•(a²+1-a²+1)=16

2a²•2=16

2a²=8

a²=4

a={4 sau -4}