To evaluate a function at a given input, you have to substitute every occurrence of the variable with that particular value.
So, for the first function, you have

The name of the variable is obviously irrelelvant, so the same goes for the second function:

Answer:
Will's age = 9 years
Bill's age = 11years
Step-by-step explanation:
Let will age = x
Bill = x +2 since he is 2 years older
x(x+2) = 5( x +x+2) - 1
Opening brackets
x² + 2x = 5(2x + 2) - 1
x² + 2x = 10x + 10 - 1
x² + 2x = 10x + 9
Collect like terms
x² + 2x - 10x - 9 = 0
x² - 8x - 9 = 0
Solve quadratically using factorisation method by finding two factors of +9 that can add up to give -8, the coefficient of x.
The factors are -9 and +1
x² + x - 9x - 9 = 0
x(x + 1) -9( x +1)
x+1) (x -9) =0
x + 1 = 0 or x -9 =0
x = -1 or 9
Age can not be negative
Therefore,
Will's age = 9 years
Bill's age = x+2 = 9+2 = 11years
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Answer:
8N - 4 border tiles.
Step-by-step explanation:
There are 4 border tiles in each corner and between the tiles there are N-2 tiles along the 4 sides.
So the number of border tiles
= 4+ 4(N - 2)
= 4 + 4N - 8
= 8N - 4.
Do a proportion. X/7/8=1/1/2. 7/8 x 1= 7/8. Now do 7/8 divided by 1/2. To do this multiply 7/8 by the reciprocal of 1/2 which is 2/1. 7 x 2= 14 and 8 x 1=8. Improper fraction is 14/8. It is 1 6/8 as a mixed number which is simplified to 1 3/4. Answer is 1 3/4