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Please help me out with my math work and explain it also if you can.

Please help me out with my math work and explain it also if you can.-example-1
User GrAnd
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1 Answer

3 votes

First question:

If f(x) = 2x+1 and g(x) = x - 3

find f - g of 4.

First combine the two functions to find what f-g is:

f(x) - g(x) = 2 x + 1 - (x - 3) = 2 x + 1 - x + 3 = x + 4

So now find the value of this expression for x=4:

f - g (4) = (4) + 4 = 8

Second question:

Is the following relation a function?

{ (1, 5) , (2, -3); (3, 5); (4, 7) }

This relationship IS a function because for every element of the Domain (1, 2, 3, and 4) there is only one associated value of y.

Third question:

If j(x) = Square root (x - 6), find j(15)

So we replace x with 15 in the function's expression:

j(15) = Square root (15 - 6) = Square root (9) = 3

Then j(15) = 3

Fourth question:

If m(x) = 3 x + 4 and n(x) = x + 2

evaluate n + m of 6

So we proceed to add the two given expressions:

n(x) + m(x) = x + 2 + 3 x + 4 = 4 x + 6

So now we estimate the value of this new expression for x = 6:

4 (6) + 6 = 24 + 6 = 30

In the case of addition or subtraction of functions, you can also do:

f(x) = 2 x + 1 and g(x) = x - 3

and to calculate f - g at x = 4, you can do:

f(4) = 2 (4) + 1 = 9

g(4) = 4 - 3 = 1

and subtract them: 9 - 1 = 8

Not sure if this is shorter or easier than the other method for you. To me they are kind of equivalent.

User RonnBlack
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6.8k points