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Solving Quadratic Equations
By The Formula Method / Exercises

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Solve the quadratic equation
3x2 + 8x + 4 = 0

ANSWER
let 3x2 + 8x + 4 = Ax2 + Bx + C
so that A = 3 , B = 8 , C = 4
Now substitue 3,8 and 4 for A,B and C respectively in the formula
x = [ -B +/- Ö(B2 - 4AC)] /2A
That is
x = [ -8 +/- Ö(82 - 4(3)(4))] /2(3)
simplifying we have :
x = [-8 +/-Ö(64 - 48)] /6
x = [-8 +/-Ö(16)] /6
x = [ -8 +/- 4 ] /6
the +/- implies
x =[ -8 + 4 ]/6
simplifying
x = -4/6
x = -2/3
or x =[ -8 - 4 ]/6
simplifying
x = -12/6
x = -2

Hence solution of 3x2 + 8x + 4 = 0 is x = -2 or -2/3

© 2004
Prakash Sukhu