Question

x² + 4x - 7 = 0
solve, and show work.

Answer 1

Okay, I love those exercises. You want to solve for x1 and x2?

Answer 2

If yes, there is a standard formula Delta = b^2-4ac.

x^2 in this case plays the role of a; 4x plays the role of b; and -7 plays the role of c

so by using that standard formula we now just have to replace everything...

Delta = 4^2 - 4*1*(-7) => Delta = 16 + 28 => Delta = 44

So now that we know Delta is not less than zero, we know it has x1, x2 solutions...

The x1, x2 solutions are also calculate by a standard formula which is -b^2 +- sqrt(delta) everything divided by 2a

so we'll have:

x1 = -16 + sqrt(44) / 2*1 = -4.6833752096446 :-)
x2 = -16 - sqrt(44) / 2* 1 = -11.3166247903554 or something like that! :D