Question

1+
4
$the \: solution \: set \: of {x}^{2} - 4x - 21 \leqslant 0 \: is$
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Answer 1

Answer:

${x}^{2} - 4x - 21 = 0 \\ \\ {x}^{2} - 7x + 3x - 21 = 0 \\ \\ x(x - 7) + 3(x - 7) = 0 \\ \\ x = 7 \\ \\ x = - 3$