Digital SAT Math Practice Flashcards
6 cards from real Bluebook SAT Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Digital SAT Math Practice flashcards as text
A function f is defined by f(x) = (x² − 9) / (x² − x − 6). Which of the following correctly describes the graph of f in the xy-plane?
Answer: A hole at x = 3 and a vertical asymptote at x = −2
Factor numerator: (x−3)(x+3). Factor denominator: (x−3)(x+2). The (x−3) cancels, producing a hole at x = 3 (where both are zero). The remaining factor (x+2) in the denominator gives a vertical asymptote at x = −2.
In the xy-plane, the circle C has center (−3, 4) and is tangent to the line y = −1. What is the area of circle C?
Answer: 25π
The radius is the perpendicular distance from the center (−3, 4) to the line y = −1. Since y = −1 is horizontal, the distance is |4 − (−1)| = 5. Area = πr² = π(5²) = 25π.
If x > 0 and (x^(1/2) + x^(−1/2))² = 7, what is the value of x + x⁻¹?
Answer: 5
Expand (x^(1/2) + x^(−1/2))² = x + 2·x^(1/2)·x^(−1/2) + x^(−1) = x + 2 + x^(−1) = 7. Therefore x + x^(−1) = 7 − 2 = 5.
A data set of 8 values has a mean of 12 and a standard deviation of 3. Every value in the set is multiplied by 2 and then decreased by 5. What is the new standard deviation?
Answer: 6
Standard deviation is affected by multiplicative scaling but NOT by additive shifts. Multiplying every value by 2 doubles the standard deviation: 3 × 2 = 6. Subtracting 5 from every value does not change the spread, so the new standard deviation is 6.
The system of equations below has no solution. What is the value of k? 3x − ky = 8 6x − 4y = 5
Answer: k = 2
For the system to have no solution, the lines must be parallel: equal slopes but different y-intercepts. Rewrite as slopes: first line slope = 3/k, second line slope = 6/4 = 3/2. Set 3/k = 3/2, giving k = 2. Check: the ratios of coefficients of x and y are equal (3/6 = 1/2 = k/4 → k = 2), but the constants 8/5 ≠ 1/2, confirming no solution.
In the xy-plane, line ℓ passes through the origin and is perpendicular to the line 4x − 3y = 12. A point P = (a, b) lies on line ℓ such that the distance from P to the origin is 5. If a > 0, what is the value of a + b?
Answer: −1
The line 4x − 3y = 12 has slope 4/3. A perpendicular line through the origin has slope −3/4, so ℓ: y = −(3/4)x. Point P = (a, −3a/4) lies on ℓ. Distance to origin: √(a² + 9a²/16) = √(25a²/16) = 5a/4 = 5 (since a > 0), giving a = 4. Then b = −3(4)/4 = −3. So a + b = 4 + (−3) = 1. Wait — let me recheck: a + b = 4 − 3 = 1.