Question 115·Easy·Nonlinear Functions
The function is defined by
What is the value of ?
For questions that ask for or for a specific number , do not expand or multiply out the entire expression first. Instead, directly substitute the given value into every , simplify each part (often each set of parentheses) step by step, and then do the final multiplication or addition. This saves time and reduces algebra mistakes, especially with minus signs and fractions like .
Hints
Start by substituting
Wherever you see in the formula for , replace it with to form an expression for .
Handle each parenthesis separately
After substituting , focus first on simplifying 2^2 - 4m{\times}2 + 7. Do not worry about the other parentheses until this one is simplified.
Simplify the second factor carefully
For 3 - \tfrac12 m{\times} 2, make sure you multiply by before subtracting, and pay attention to the minus sign in front of .
Combine your results
Once both parentheses are simplified to single numbers, multiply those two numbers to get the value of .
Desmos Guide
Enter the function into Desmos
Type g(x) = (x^2 - 4x + 7)(3 - 1/2 x) into a new Desmos line so Desmos defines the function .
Evaluate the function at
In a new line, type g(2) and look at the numerical value Desmos displays; that value is the correct value of .
Step-by-step Explanation
Substitute into the function
Start with the definition of the function:
To find , replace every with :
Simplify the first set of parentheses
Now simplify the expression 2^2 - 4m{\times}2 + 7 step by step:
- 4m{\times}2 = 8
So
Compute this:
So the first factor becomes .
Simplify the second set of parentheses
Next simplify 3 - \tfrac12 m{\times} 2:
- \tfrac12 m{\times} 2 = 1
So
Now the expression for is
Multiply the two factors to get
Finally, multiply the two simplified factors:
- 3 m{\times} 2 = 6
So
This corresponds to answer choice B) 6.