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Question
Solve the following equation by factorization
21x2 – 8x – 4 = 0
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Solution
21x2 – 8x – 4 = 0
⇒ 21x2 - 14x + 6x - 4 = 0
⇒ 7x (3x - 2) + 2 (3x - 2) = 0
⇒ (3x - 2) (7x + 2) = 0
Either 3x - 2 = 0,
then 3x = 2
⇒ x = `(2)/(3)`
or
7x + 2 = 0,
then 7x = -2
⇒ x = `(-2)/(7)`
Hence x = `(2)/(3), (-2)/(7)`.
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