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Question
Solve the following quadratic equation by the formula method:
x2 + 10x + 2 = 0
Solution
x2 + 10x + 2 = 0
Compare the given equation with
ax2 +bx+ c = 0
a = 1, b = 10, c = 2
b2 − 4ac = (10)2 – 4 × 1 × 2
= 100 – 8
b2 − 4ac = 92
x = `(-b ± sqrt(b^2 - 4ac))/(2a)`
= `(-10 ± sqrt(92))/(2 xx 1)`
= `(-10 ± sqrt(4 xx 23))/2`
= `(-10 ± 2sqrt(23))/2`
= `(-10)/\2 ± 2/2 sqrt(23)`
= `-5 ± sqrt(23)`
x = `-5 + sqrt(23)` or x = `-5 - sqrt(23)`
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