AlgebraMediumInput at which a linear function is half its starting value
Algebra practice question
The function f is defined by f(x) = −(2/5)x + 6. For what value of x is f(x) equal to half of f(0)?
Answer: 15/2 or 7.5
f(0) = 6, so half is 3: −(2/5)x + 6 = 3 → (2/5)x = 3 → x = 15/2.
Common wrong answers
- If you answered 3
- 3 is the target value, not x.
- If you answered 15
- 15 is where f(x) = 0, not 3.
- If you answered 1.2
- 1.2 comes from (2/5) × 3, multiplying instead of dividing.
More Algebra questions
- Medium
A system: 2x + y = 11 and x − y = 1. What is the value of x + y? - Medium
Which of the following describes all solutions to 4x − 9 ≤ 2x + 5? - Medium
A phone's battery percentage is modeled by P = 100 − 8t, where t is the number of hours since it was unplugged… - Medium
If y = 2x − 1 and 3x + y = 14, what is the value of x? - Medium
If |2x − 3| = 7, what is the sum of all possible values of x? - Medium
Line k has equation y = (2/3)x + 1. Which equation represents a line perpendicular to line k?
Not affiliated with the College Board. SAT is a trademark of the College Board.