12x-y when x= 1/3, y=-2
2 answers:
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Answer:
Step-by-step explanation:
Given the following function:
You need to follow these steps in order to solve the exercise:
1. Substitute :
2. Now you need to apply the Quadratic formula. This is:
In this case, you can identify that:
Then, you can substitute these values into the formula:
3. Evaluating, you get:
4. You must choose the positive value. Then:
Actually, the answer is not A, if you're saying A is the first choice above. That's incorrect. You will need to use the Geometric mean for right triangles here to figure out what the value of a is. We will use this form: 
. We have a value for YZ of 3; side a is XZ. That means in order to solve this we need WZ, which we can find using pythagorean's theorem. 3^2 + 4^2 = c^2 and 9 + 16 = c^2 and c = 5. Now we fill in accordingly: 
. Cross-multiply to get 3XZ=25 and side XZ is 
. XZ is 25/3 and YZ is 3, so 25/3 - 3 = XY. That means that XY (side a) = 16/3 or 5 1/3, choice B, or the second one down.