Question

a^3 _ 2a^2 _ 5a _ 6 =0

Answer 1

${a}^{3} - 2 {a}^{2} - 5a - 6 = 0 \\ a( {a}^{2} - 2a - 5) - 6 = 0 \\ {a}^{2} - 2a - 5 - 6 = 0 \div a \\ {a}^{2} - 2a - 5 - 6 = 0 \\ {a}^{2} - 2a - 11 = 0 \\ a(a - 2) - 11 = 0 \\ a - 2 - 11 = 0 \div a \\ a - 2 - 11 = 0 \\ a - 13 = 0 \\ a = 0 + 13 \\ a = 13$
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