If given this question on the test, the first thing I would notice is that every answer choice is an integer ———> means we are looking for integer values for X and Y, more than likely
The first thing we can definitely do is eliminate the term of:
+ 4 (y - 3)^2
The output of a square will always be positive or 0 —— so if y = any other value than +3, we will be adding a positive value to the overall expression. We went to minimize, so make y = +3 so that this one expression drops out.
Minimize:
4 * (x - 2)^2 - 2 * (x - 3)^2
Whenever you subtract two numbers you can think of the subtraction as finding the distance on the number line between the 2 numbers being subtracted.
We also have the exponential effect of the squaring ——— we want X to be as far away from +3 as we can make it, without going so far as to allow the positive effect of +4 * (x - 2)^2 to overcome the magnitude of the negative value provided by -2 * (x - 3)^2
The first place to start is the following: make the distance from +2 —-> distance of zero so that the positive effect from +4 * (x - 2)^2 completely drops out
When X = +2
4 * (2 - 2)^2 - 2 * (2 - 3)^2 =
-2 * (-1)^2 =
-2
So we can eliminate two answers - D and E
As we move further left on the number line from +2, there will come a point at which the exponential effect of the squaring and *4 factor will lead to the positive magnitude of +4 (x - 2)^2 overcoming the negative magnitude of -2 * (x - 3)^2
When X = 1
4 * (-1)^2 - 2 * (-2)^2 =
4 - 8 =
-4
We can eliminate C as the minimization
Now all we need to decide is whether we can get the expression to equal = -8
When X = 0
4 * (-2)^2 - 2 * (-3)^2 =
16 - 18 =
-2
As we keep moving left on the number line, the positive value of +4 (x - 2)^2 will keep becoming relatively more and more larger in magnitude compared to -2 (x - 3)^2
Answer:
(B)
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