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Question
Find the roots of the following equation, if they exist, by applying the quadratic formula:
x2 + x + 2 = 0
Sum
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Solution
Given: x2 + x + 2 = 0
Step-wise calculation:
1. Compare with ax2 + bx + c = 0:
a = 1, b = 1, c = 2
2. Quadratic formula:
`x = (-b ± sqrt(b^2 - 4ac))/(2a)`
3. Compute discriminant:
D = b2 – 4ac
= 12 – 4(1)(2)
= 1 – 8
= –7
4. Substitute:
`x = (-1 ± sqrt(-7))/2`
= `(-1 ± isqrt(7))/2`
The equation has no real roots; its two complex conjugate roots are `x = (-1 + isqrt(7))/2` and `x = (-1 - isqrt(7))/2`.
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