Which is the graph of a quadratic equation that has a negative discriminant?
2 answers:
Answer:
The correct graph is D.
Step-by-step explanation:
Given a quadratic equation :
You can find the roots (where the graph intersects the x-axis) applying the following equation :
and
We define the discriminant as
If then the graph will intersect the x-axis in two points
If then the graph will intersect the x-axis in one point.
Finally, If then the graph won't intersect the x-axis because it will not have real roots.
In this exercise, the graph that doesn't intersect the x-axis is graph D.
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The given sequence is
a₁, a₂, ...,
Because the given sequence is an arithmetic progression (AP), the equation satisfied is
where
d = the common difference.
The common difference may be determined as
d = a₂ - a₁
The common difference is the difference between successive terms, therefore
d = a₃ - a₂ = a₄ - a₃, and so on..
The sum of the first n terms is
Example:
For the arithmetic sequence
1,3,5, ...,
the common difference is d= 3 - 1 = 2.
The n-th term is
For example, the 10-term is
a₁₀ = 1 + (10-1)*2 = 19
Th sum of th first 10 terms is
S₁₀ = (10/2)*(1 + 19) = 100
a₁, a₂, ...,
Because the given sequence is an arithmetic progression (AP), the equation satisfied is
where
d = the common difference.
The common difference may be determined as
d = a₂ - a₁
The common difference is the difference between successive terms, therefore
d = a₃ - a₂ = a₄ - a₃, and so on..
The sum of the first n terms is
Example:
For the arithmetic sequence
1,3,5, ...,
the common difference is d= 3 - 1 = 2.
The n-th term is
For example, the 10-term is
a₁₀ = 1 + (10-1)*2 = 19
Th sum of th first 10 terms is
S₁₀ = (10/2)*(1 + 19) = 100