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Solve $x^{2} + 10 x + 21 = 0$ by completing the square. The smaller root is:

Class 10Completing the SquareQuadratic Equations

A-6
B-8
C-7
D-14

Step-by-Step Solution

x^{2} + 10 x = - 21

, add 25:

(x + 5)^{2} = 4, x + 5 = + / - 2, x = - 3

or

x = - 7

. Smaller is -7.

Answer: C) -7

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