Let H be a Hilbert space and A a positive self-adjoint operator on H. Prove that the following assertions are equivalent: (i) A(H) is dense in H. (ii) Ker A = {0}. (iii) A is positive definite, i.e., (Ax, x) > 0, Vx H\ {0}.

Advanced Engineering Mathematics
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Chapter2: Second-order Linear Odes
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Let H be a Hilbert space and A a positive self-adjoint operator on H. Prove that
the following assertions are equivalent:
(i) A(H) is dense in H.
(ii) Ker A = {0}.
(iii) A is positive definite, i.e., (Ax,x) > 0, Vx € H\ {0}.
Transcribed Image Text:Let H be a Hilbert space and A a positive self-adjoint operator on H. Prove that the following assertions are equivalent: (i) A(H) is dense in H. (ii) Ker A = {0}. (iii) A is positive definite, i.e., (Ax,x) > 0, Vx € H\ {0}.
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