Answer:
A
Step-by-step explanation:
Recall that for a quadratic equation of the form:
[tex]0=ax^2+bx+c[/tex]
The number of solutions it has can be determined using its discriminant:
[tex]\Delta = b^2-4ac[/tex]
Where:
- If the discriminant is positive, we have two real solutions.
- If the discriminant is negative, we have no real solutions.
- And if the discriminant is zero, we have exactly one solution.
We have the equation:
[tex]2x^2+5x-k=0[/tex]
Thus, a = 2, b = 5, and c = -k.
In order for the equation to have exactly one distinct solution, the discriminant must equal zero. Hence:
[tex]b^2-4ac=0[/tex]
Substitute:
[tex](5)^2-4(2)(-k)=0[/tex]
Solve for k. Simplify:
[tex]25+8k=0[/tex]
Solve:
[tex]\displaystyle k = -\frac{25}{8}[/tex]
Thus, our answer is indeed A.
