Which of the following equations is quadratic?
1 answer:
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Answer:
5 times as large
Step-by-step explanation:
You can think of "10^5" as "green marbles" if you like. Then your question is ...
5 green marbles is how many times as large as 1 green marble.
Hopefully, the answer is all too clear: it is 5 times as large.
_____
In math terms, when you want to know how many times as large y is as x, the answer is found by dividing y by x:
y/x . . . . . tells you how many times as large as x is y.
Here, that looks like ...
1) Answer: 21
As y varies directly with x, this means that the ratio y/x is always a constant.
In other words, the equation can be written as y = kx, where k is a constant term.
Thus,
y = 21
2) Answer: C
Exactly the same process as above.
Here's another method:
25 = k(140)
k = 25/140 = 5/28
Thus, when y = 36, 36 = kx
36 = 5/28(x)
36 * 28/5 = x; x = 201.6
3) 9 = k(12)
9/12 = k and k = 3/4
4) On the graph, it hits y = 1 at x = 4.
Thus, we can rewrite the equation as:
y = (1/4)x, where the constant term is 1/4
5) y = kx
The distance represents the x-ordinates, and the time represents the y-ordinates.
9.5/475 = 0.02
4 = 0.02(x), in hours.
x = 200 miles.
As y varies directly with x, this means that the ratio y/x is always a constant.
In other words, the equation can be written as y = kx, where k is a constant term.
Thus,
y = 21
2) Answer: C
Exactly the same process as above.
Here's another method:
25 = k(140)
k = 25/140 = 5/28
Thus, when y = 36, 36 = kx
36 = 5/28(x)
36 * 28/5 = x; x = 201.6
3) 9 = k(12)
9/12 = k and k = 3/4
4) On the graph, it hits y = 1 at x = 4.
Thus, we can rewrite the equation as:
y = (1/4)x, where the constant term is 1/4
5) y = kx
The distance represents the x-ordinates, and the time represents the y-ordinates.
9.5/475 = 0.02
4 = 0.02(x), in hours.
x = 200 miles.