bry856 one year ago The roots of an equation are x = -1 ± i. The equation is x^2 + _____ + 2 = 0.

1. sdfgsdfgs

"The roots of an equation are x = -1 ± i. " so the eqn is (x-(-1+i))*(x-(-1-i)) = 0 expend the above n simply...what will u get?

2. jim_thompson5910

Let p and q be the roots of $$\Large x^2 + bx + c = 0$$ Rule: $$\Large p+q = -b$$ so $$\Large b = -(p+q)$$

3. campbell_st

well if you think about the general quadratic formula $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$ you can see from the equation a = 1 and c = 2 so $x = \frac{-b \pm \sqrt{b^2 - 4 \times 1 \times 2}}{2 \times 1}$ then comparing the parts $-1 = \frac{-b}{2}$ solve for b... and then check with b by using the rest of the quadratic formula $b^2 - 8 = \frac{\sqrt{4i^2}}{2}$