Find all of the real zeros of the function. Give exact values whenever possible. Identify each zero as rational or irrational.
-$$f ( x ) = x ^ { 3 } - 3 x ^ { 2 } - 7 x + 21$$
A) 3 (rational), 7 (rational), and $- 7$ (rational)
B) 3 (rational), $2 \sqrt { 7 }$ (irrational), and $- 2 \sqrt { 7 }$ (irrational)
C) 3 (rational), $\sqrt { 7 }$ (irrational), and $- \sqrt { 7 }$ (irrational)
D) $- 3$ (rational), $\sqrt { 7 }$ (irrational), and $- \sqrt { 7 }$ (irrational)

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The Answer of Find all of the real zeros of the function. Give exact values whenever possible. Identify each zero as rational or irrational.
-$$f ( x ) = x ^ { 3 } - 3 x ^ { 2 } - 7 x + 21$$
A) 3 (rational), 7 (rational), and $- 7$ (rational)
B) 3 (rational), $2 \sqrt { 7 }$ (irrational), and $- 2 \sqrt { 7 }$ (irrational)
C) 3 (rational), $\sqrt { 7 }$ (irrational), and $- \sqrt { 7 }$ (irrational)
D) $- 3$ (rational), $\sqrt { 7 }$ (irrational), and $- \sqrt { 7 }$ (irrational)

Find All of the Real Zeros of the Function f(x)=x3−3x2−7x+21f ( x ) = x ^ { 3 } - 3 x ^ { 2 } - 7 x + 21f(x)=x3−3x2−7x+21

Find All of the Real Zeros of the Function $f ( x ) = x ^ { 3 } - 3 x ^ { 2 } - 7 x + 21$