O lvl A Maths: Quadratic Equations

Find the value of m if the roots of the quadratic equation x² + 2mx + m + 2 = 0 are equal

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Answer:

When the roots are equal, discriminant (b²-4ac) = 0

In this case, a = 1, b = 2m and c = m+2

b² - 4ac = 4m² - 4(1)(m+2) = 0
4m² - 4m - 8 = 0
m² - m - 2 = 0
(m-2)(m+1) = 0
m = 2 or -1

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