Question

BRAINLIEST AVAILABLE!!!! PLEASE HELP ME WITH THIS!!! Thanks to all helpers!!!!!

Answer 1

Answer: B

Step-by-step explanation:

-10x² + 12x - 9 = 0

a=-10, b=12, c=-9

x = $\frac{-b+/-\sqrt{b^{2}-4ac}} {2a}$

  = $\frac{-12+/-\sqrt{12^{2}-4(-10)(-9)}} {2(-10)}$

  = $\frac{-12+/-\sqrt{144-360}} {-20}$

  = $\frac{-12+/-\sqrt{-216}} {-20}$

  = $\frac{-12} {-20}$ +/- $\frac{\sqrt{-216}} {-20}$

  = $\frac{3} {5}$ +/- $\frac{6i\sqrt{6}} {-20}$

  = $\frac{3} {5}$ +/- $\frac{3i\sqrt{6}} {10}$

Answer 2

The easiest way to begin this problem is to multiply through by minus one. It will not change the answer. Then use the quadratic formula. It looks like it cannot be factored just by doing it.

Solution

-1(-x^2 + 12x - 9) = 0 * -1

x^2 - 12x + 9 = 0

$\text{x = }\dfrac{ -b \pm \sqrt{b^{2} - 4ac } }{2a}$

a = 10; b = - 12 ; c = 9

$\text{x = }\dfrac{ -(-12) \pm \sqrt{((-12)^{2} - 4*10*9 )} }{2*10}$

$\text{x = }\dfrac{ (12) \pm \sqrt{(144)-360)}}{20}$

$\text{x = }\dfrac{ (12) \pm \sqrt{(-216)}}{20}$

216 has to be put into prime factors to see how much can come out of the root sign

216:2 * 2 *2 * 3 * 3 * 3

$\text{x = }\dfrac{ (12) \pm \2*3sqrt{(-6)}}{20}$

x  = 12/20 +/- (6/20)i sqrt(6)

x = 3/5 +/- (3/10)*i*sqrt(6) which is B

B: Answer