Function Substitution and Equation Solving

This video tutorial guides viewers through solving a practice SAT math question involving functions. The problem requires determining the values of a function for given expressions and solving the resulting equation for the variable 'a'. The tutorial explains each step, from substituting values into the function to simplifying and solving the equation, ultimately finding the solution and concluding with the correct answer choice.

What is the function f(x) defined as in the problem?

• f(x) = x - 9

• f(x) = x + 9

• f(x) = x / 9

• f(x) = 9x

What is the expression for f(5a) when substituting into the function?

• 5a * 9

• 9a + 5

• 5a - 9

• 5a + 9

What is the expression for f(3a) when substituting into the function?

• 3a - 9

• 3a * 9

• 9a + 3

• 3a + 9

After substitution, what is the equation formed on the left side?

• 5a + 3

• 5a + 12

• 5a + 20

• 5a + 9

After substitution, what is the equation formed on the right side?

• 3a + 20

• 3a + 11

• 3a + 9

• 3a + 12

What is the result after subtracting 3a from both sides of the equation?

• 2a + 9 = 8

• 2a + 12 = 20

• 2a + 9 = 20

• 2a + 12 = 8

What is the value of 'a' after solving the equation?

• 2

• 6

• 8

• 4

Which option corresponds to the correct answer for 'a' in the choices given?

• Option B

• Option A

• Option E

• Option C