The annual interest on an $20,000 investment exceeds the interest earned on a $4000 investment by $1320. The $20,000 is invested
1 answer:
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First, we are going to find the vertex of our quadratic. Remember that to find the vertex 
of a quadratic equation of the form 
, we use the vertex formula 
, and then, we evaluate our equation at 
to find 
.
We now from our quadratic that
and 
, so lets use our formula:
Now we can evaluate our quadratic at 8 to find:
So the vertex of our function is (8,-72)
Next, we are going to use the vertex to rewrite our quadratic equation:
The x-coordinate of the minimum will be the x-coordinate of the vertex; in other words: 8.
We can conclude that:
The rewritten equation is
The x-coordinate of the minimum is 8
We now from our quadratic that
Now we can evaluate our quadratic at 8 to find
So the vertex of our function is (8,-72)
Next, we are going to use the vertex to rewrite our quadratic equation:
The x-coordinate of the minimum will be the x-coordinate of the vertex; in other words: 8.
We can conclude that:
The rewritten equation is
The x-coordinate of the minimum is 8
Answer:
(-4,2) belongs in this direct variation.
Step-by-step explanation:
Let the direct variation relationship is expressed by the equation y = mx ........ (1), where x and y are in direct variation and k is the variation constant.
Now, the point (4,-2) is included in the direct variation relationship, then from equation (1) we get, -2 = 4m
⇒
Therefore, the equation (1) becomes
⇒ x + 2y = 0 ......... (2)
Now, from the given four options only the point (-4,2) satisfies the relation (2).
Hence, (-4,2) belongs in this direct variation. (Answer)