Question

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Find the roots of the quadratic equation x2 - 4x – 21 = 0 by formula
method

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Answer 1

Answer:

The roots of the quadratic equation is -7 and -3

Step-by-step explanation:

x^2-4x-21=0

x^2-(7-3)x-21=0

x^2-7x+3x-21=0

x(x-7)+3(x-7)=0

(x-7)(x+3)=0

either, x+7=0 , x= -7

or, x+3=0. , x= -3