How do you find the value of the discriminant and state the type of solutions given $-x^2-9=6x$ ?

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Answer 1 · 2017-11-15T10:37:42

Solution: $x=-3$

$-x^2-9=6x or -x^2-6x-9=0$

Comparing with standard quadratic equation $ax^2+bx+c=0$

$a=-1 ,b=-6 ,c=-9$ Discriminant $D= b^2-4ac$ or

$D=36-36 =0$ If discriminant positive, we get two real solutions,

if it is zero we get just one solution, and if it is negative we get

complex solutions. Discriminant is zero , so it has one root .

Quadratic formula: $x= (-b+-sqrtD)/(2a)$ or

$x= (6+-sqrt0)/(-2) = -3$

Solution: $x=-3$ [Ans]

How do you find the value of the discriminant and state the type of solutions given -x^2-9=6x-x^2-9=6x?