By quadratic equation x2 + x - 420 ,we get, x= 20 and x=-2. here does it have two solution or one solution ?

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Solution

$The given quadratic equation is, x^{2} + x - 420 = 0 \Rightarrow x^{2} + 21 x - 20 x - 420 = 0 \Rightarrow x (x + 21) - 20 (x + 21) = 0 \Rightarrow (x - 20) (x + 21) = 0 \Rightarrow x - 20 = 0 or x + 21 = 0 \Rightarrow x = 20 or x = - 21 So, 20 and - 21 are the solutions of the given quadratic equation . Since, Quadratic equation involves a quadratic polynomial of degree 2, so, it has only 2 solutions .$

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