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Suppose that set \( A \) is equivalent to set \( B=\left\{(x, y) \in \mathbb{R}^{2}: x^{2}+y^{2}=1 ...
Suppose that set \( A \) is equivalent to set \( B=\left\{(x, y) \in \mathbb{R}^{2}: x^{2}+y^{2}=1\right\} \). Let \( C=\left\{(x, y) \in \mathbb{R}^{2}:\left(\frac{x}{2}\right)^{2}+\left(\frac{y}{3}\right)^{2}=1\right\} \) (1) [2 points] Prove that if mappings \( f: A \longrightarrow B \) and \( g: B \longrightarrow C \) are injective, then the composition \( g \circ f: A \longrightarrow C \) must be injective. (2) [2 points] Prove that if mappings \( f: A \longrightarrow B \) and \( g: B \longrightarrow C \) are surjective, then the composition \( g \circ f: A \longrightarrow C \) must be surjective. (3) [6 points] Prove or disprove that sets \( A \) and \( C \) are equivalent. If you think that the statement is true, then make use of part (1) and part (2) above. Construct mapping \( g: B \longrightarrow C \).