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Solve using formula. 5m2 – 4m – 2 = 0 - Algebra

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Question

Solve using formula.

5m2 – 4m – 2 = 0

Sum

Solution

5m2 – 4m – 2 = 0 compare with ax2 + bx + c = 0, we get

⇒ a = 5, b = – 4 and c = - 2

∴ b2 - 4ac = (- 4)2 - 4 (5)(- 2)

= 16 - (-40)

= 16 + 40

= 56

We have the formula,

`m = (-b ± sqrt(b^2 - 4ac))/(2a)`

Substituting the values in the formula, we get,

⇒ m = `(-(-4) ± sqrt(56))/(2 xx 5)`

⇒ m = `(4 ± sqrt(4 xx 14))/(2 xx 5)`

⇒ m = `(4 ± 2sqrt(14))/(2 xx 5)`

⇒ m = `(2(2 ± sqrt14))/(2 xx 5)`

⇒ m = `(2 ± sqrt 14)/(5)`

The roots are

⇒ `m = (4 + 2sqrt(14))/10 "or"  m = (4 - 2sqrt(14))/10` 

⇒ `m = (2 + sqrt(14))/5 "or"  m = (2 - sqrt(14))/5`

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Chapter 2: Quadratic Equations - Practice Set 2.4 [Page 43]

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