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Question
Solve the following quadratic equation using formula method only
`"x"^2 - 4 sqrt 15 "x" - 4 = 0`
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Solution
`"x"^2 - 4 sqrt 15 "x" - 4 = 0`
a = 1 ; b = `- 4 sqrt 15` ; c = -4
D = b2 - 4ac
= `(- 4 sqrt 15)^2 - 4(1)(-4)`
= 240 + 16
= 256
x = `(- "b" ± sqrt ("b"^2 - 4 "ac"))/(2a)`
x = `(4 sqrt 15 +- sqrt 256)/2`
x = `(4 sqrt 15 + 16)/2` , x = `(4 sqrt 15 - 16 )/2`
x = `2 sqrt 15 + 8` , x = `2 sqrt 15 - 8`
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