Question

help me solve x2 – 4x – 8 = 0

Answer 1

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Answer 2

This is a quadratic equation that you can solve by factoring or applying quadratic formula, or completing a square method.

If you can factor the equation, then that's the way to go. Otherwise, apply quadratic formula.

Answer 3

\[-b \pm \sqrt{b^2-4ac}/2a\]

Answer 4

this does not factorise

so u can use completing the square or the formula

Answer 5

do you understand the formula?

Answer 6

not really

Answer 7

ok
the general formula for a quadratic (whch u have here) is

ax^2 + bx + c = 0
and u plug in the values of a, b and c into the formula which Lagrange has quoted above

so in this case a = 2, b = -1 and c = -8
put these values into the formulas and u will get the solutions

Answer 8

x = (-b +/- sqrt(b^2 - 4ac)) / 2a

x = (-4 +/- sqrt(16 - 4*1*8)) / 2

x = (-4 +/- sqrt(-16)) / 2

x = (-4 +/- 4i) / 2

x = -2 +/- 2i

Answer 9

sorry b = -4 not -1

Answer 10

you've got a little wrong there lady - check your sqrt bit again

Answer 11

ok thanks

Answer 12

a=1

Answer 13

oh yeah a = 1