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1 answer:
To me personally, the first bit f(g(x)) is easy and the domain is tricky. Let's try explain this.
A function takes an input number and returns an output number depending on the function. Look at f(x) = x+3, if we let the input number be 2 then we say that f(2) = 5. We could do f(π) to give us π+3 or even f(x²) to give us x² +3. The trick is to substitute the input into the function equation.
You have been asked to find f(g(x)). You know f(x) =
. Putting numbers in at this point would be easy (try work out f(2), you'll do it really quick) but you have to put in g(x).
f(g(x)) =
we also know that g(x) =
so we can say that
f(g(x)) =
and that is f(g(x)) but the question requires that we simplify it so
f(g(x)) =
Now for the tricky bit (for me, at least). The domain is the full set of values that you can 'put in to' the function and still get a real value out. So how do we work out what numbers 'break' the function? I like to use the fact that DIVIDING BY ZERO IS IMPOSSIBLE. What value of x can we put into the function to make it so the function is being divided by 0? i.e. 1-2x = 0 solve that and you have a value of x that isn't part of the domain.
This means the domain is all real numbers EXCEPT the solution to that equation. (Because if we put that value into f(g(x)) it's impossible to get a value out.)
[I know this was a lot to read, if you have any questions or don't get anything feel free to message me or leave a comment.]
A function takes an input number and returns an output number depending on the function. Look at f(x) = x+3, if we let the input number be 2 then we say that f(2) = 5. We could do f(π) to give us π+3 or even f(x²) to give us x² +3. The trick is to substitute the input into the function equation.
You have been asked to find f(g(x)). You know f(x) =
f(g(x)) =
we also know that g(x) =
f(g(x)) =
f(g(x)) =
Now for the tricky bit (for me, at least). The domain is the full set of values that you can 'put in to' the function and still get a real value out. So how do we work out what numbers 'break' the function? I like to use the fact that DIVIDING BY ZERO IS IMPOSSIBLE. What value of x can we put into the function to make it so the function is being divided by 0? i.e. 1-2x = 0 solve that and you have a value of x that isn't part of the domain.
This means the domain is all real numbers EXCEPT the solution to that equation. (Because if we put that value into f(g(x)) it's impossible to get a value out.)
[I know this was a lot to read, if you have any questions or don't get anything feel free to message me or leave a comment.]
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A square has 4 equal sides, which means when you need to work out the area, you're doing length × width, but the length and width are exactly the same, because it's a square (look at the picture if you don't understand this).
That means you just have to pick any side (let's call this side x), and multiply it by another side of the square. Now, because all of the sides are equal, you're doing x multiplied by x, which is the same as x².
Therefore, if the area is equal to x², and in this question, it's also equal to 49 (as stated in the question), we can equate them to each other:
x² = 49
Now to get the x by itself, we need to do the opposite of squaring, which is square rooting. Therefore, we square root both sides of the equation:
√x² = √49
The √ and the ² cancel out, so you're just left with x:
x = √49
The square root of 49 is just 7, so we can replace √49 with 7, and we get:
x = 7
Now remember, earlier, I called x the value of one side. Therefore, by remembering that, you know that the value of one side is equal to 7. And because all the sides are the same as each other, each side is equal to 7 metres.
Therefore, your final answer is 7 metres :)
