maths higher help, functions?

Question

i have forgotten how to do functions so could anyone tell me how to do this

f(x) = x^2 - a and g(x) = ax - 2 where a is a constant

given that f(2) = g(2), find the value of a?

do i sub in 2 then equate to 0? thanks for any help and solutions you get

Answer 1

The condition is that

x^2 - a = ax - 2 when x=2

So, 4 - a = 2a - 2

So, 6 = 3a and therefore a = 2

OK?

Answer 2

f(2) = 2^2 -a = 4 - a

g(2) = 2a - 2

if g(2) = f(2) then
2a -2 = 4 - a
=> 2a +a = 4 +2
=> 3a = 6
=> a = 2

so f(x) = x^2 - 2
and g(x) = 2x - 2

Answer 3

Im not sure about equating to 0, but here's how i'd do it:
so f(2)=g(2) therefore
4-a=2a-2
3a=6
a=2

Answer 4

make to equations equan and use the given parameters in their respective eq

f(2) =g(2)
(2)^2-a= a*(2) -2

4-a=2 * a-2
2= a

and your done :)