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Mathematics 8 Online
OpenStudy (anonymous):

I just want to get this done so I can sleep. ): Please help):

OpenStudy (anonymous):

Question 1- Identify the domain of the equation y = x2 − 6x + 1. (1 point) x ≤ 3 x ≥ −8 x ≥ −2 All real numbers Question 2- Functions f(x) and g(x) are shown below: f(x) = x2 g(x) = x 2 + 8x + 16 In which direction and by how many units should f(x) be shifted to obtain g(x)? (1 point) Left by 4 units Right by 4 units Left by 8 units Right by 8 units

OpenStudy (anonymous):

@Luigi0210 @sleepyjess @maryfitzgerald14 @jim_thompson5910 @Kainui @El_Arrow

OpenStudy (hitaro9):

So for question one, keep in mind that the domain is essentially all the numbers that you can plug in to an equation, and get a valid number out. So for that, you can go ahead and just try some different numbers. Say, x= 2 (Which is less than 3). Plug this in you get ((3)^2 -6(3) +1) Which is just 9-18+1 which is -8, which is a real number.

OpenStudy (hitaro9):

You can try for other numbers that would satisfy the others, and find that you get a real number back every time (feel free to go ahead and plug some examples in like I did). You'll find that all numbers you put in can be squared, all numbers can be multiplied by 3, and all numbers can be added and subtracted

OpenStudy (hitaro9):

Thus the domain is all real numbers.

OpenStudy (anonymous):

Thank you!(: Also thank you for explaining it! Can you explain the second one also?

OpenStudy (hitaro9):

Sure. So, there are 2 "Basic" things you can do to an equation, you can move it up/down, and you can move it left/right.

OpenStudy (hitaro9):

Moving it up/down is pretty simple. You just add numbers to the equation to shift the whole thing (think y=mx+b. Adding b just moving y=mx up to b, and subtracting b just moves it down to b).

OpenStudy (hitaro9):

Moving it left and right is probably a bit less intuitive.

OpenStudy (hitaro9):

But essentially, what you want to do it subtract from just the "x" portion of the equation.

OpenStudy (hitaro9):

By adding or subtracting from just the "x" part, you are essentially telling the function "Use the x from somewhere else on the number line"

OpenStudy (hitaro9):

Which is going to move your x left or right.

OpenStudy (hitaro9):

So for the equation, f(x) + x^2

OpenStudy (hitaro9):

You're just adding or subtracting from the x part.

OpenStudy (hitaro9):

So it's going to be g(x) = (x+h)^2

OpenStudy (hitaro9):

Now, you might be thinking "that doesn't look like any of our options" but keep in mind, that you can expand that to be x^2 +2h +16

OpenStudy (hitaro9):

or my bad, x^2 +2h + h^2

OpenStudy (hitaro9):

So from there, it should be obvious that 8 or -8 is not going to be the answer, right? Cause that'd leave you with something like x^2 + 16 + 64 which looks nothing like our original equation

OpenStudy (hitaro9):

x^2 +16x +64*

OpenStudy (hitaro9):

So it's got to be either h=4 or h=-4

OpenStudy (hitaro9):

It's going to be h=4 if you just work it out. So let's think about how that affects the equation

OpenStudy (hitaro9):

So now you've got to think "What does adding 4 to x tell the equation to do?"

OpenStudy (hitaro9):

Well, it's telling the equation to use numbers for x from 4 in the past, essentially, right?

OpenStudy (anonymous):

yes

OpenStudy (hitaro9):

So that's going to move the equation 4 units to the left.

OpenStudy (anonymous):

Thank you so much for helping me understand(:

OpenStudy (hitaro9):

Yep. You understand the thought process right? Think you could solve this type of problem on a test?

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