Perform the indicated operation

Question

f(x)=2x-1

g(x)=x+4

find (f-g)(-9)

Answer 1

One approach to take with this problem is to first find the rule for (f - g)(x). Given the rules for f(x) and g(x), the rule for ( f - g )(x) would be ( 2x - 1) - ( x + 4 ) which simplifies to x - 5. Now that we have the rule for ( f - g )(x), we can use the rule to evaluate at x = -9 and this gives us the final value of -14.

Answer 2

f(x) = 2x-1

=> f(-9) = 2(-9)-1 = -19

g(x) = x + 4

=> g(-9) = -9 + 4 = -5

(f-g)(-9) = -19 - (-5) = -14