SAT Math Practice Test: Advanced Math
- Advanced Math
- 11 questions
- 15 minutes
These questions cover SAT Advanced Math: equivalent expressions, quadratic and exponential functions, polynomials, radical equations and graphs of nonlinear functions. After squaring both sides of an equation, check every solution in the original equation.
Tap an option to mark your answer. You can change your mind, or tap the same option again to leave the question blank. The correct answers and explanations appear when you finish the test.Tap an option to answer; tap it again to leave the question blank.
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Question 1
Which expression is equivalent to (2x − 3)2 − (x + 1)(x − 1)?
Correct answer: A
(2x − 3)2 = 4x2 − 12x + 9 and (x + 1)(x − 1) = x2 − 1. Subtracting gives 3x2 − 12x + 10; the choice ending in + 8 forgets that subtracting −1 adds 1.
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Question 2
The function f is defined by f(x) = (x − 1)(x − 7). What is the minimum value of f(x)?
Correct answer: A
The parabola opens upward, and its vertex lies halfway between the zeros 1 and 7, at x = 4. The minimum value is f(4) = (3)(−3) = −9; the choice 4 is the x-coordinate of the vertex, not the minimum value.
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Question 3
What is the positive solution to the equation 2x2 + 5x − 12 = 0?
Correct answer: B
Factoring gives (2x − 3)(x + 4) = 0, so x = 32 or x = −4. The positive solution is 32; the choice 4 comes from reading the factor x + 4 with the wrong sign.
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Question 4
The number of bacteria in a culture t hours after an experiment begins is modeled by P(t) = 500(1.08)t. Which statement is the best interpretation of the number 1.08 in this model?
Correct answer: B
Multiplying by 1.08 every hour means each hour adds 8% of the current amount. A 108% increase would mean multiplying by 2.08, and an increase of exactly 8 bacteria per hour would be a linear model.
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Question 5
A radioactive sample has an initial mass of 80 grams. Its half-life is 6 days, which means its mass is halved every 6 days. Which function gives the mass M, in grams, of the sample after d days?
Correct answer: D
The mass is multiplied by 0.5 once every 6 days, so the exponent counts the number of 6-day periods, d/6. Check: when d = 6, M = 80(0.5)1 = 40. The exponent 6d would halve the mass six times every day.
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Question 6
p(x) = x3 − 4x2 + kx − 6
In the polynomial shown, k is a constant. If x − 3 is a factor of p(x), what is the value of k?
Correct answer: C
If x − 3 is a factor, then p(3) = 0: 27 − 36 + 3k − 6 = 0, so 3k = 15 and k = 5. The choice 15 is the value of 3k, not k.
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Question 7
What are all the solutions to the equation x + 7 = x − 5?
Correct answer: B
Squaring gives x + 7 = x2 − 10x + 25, so x2 − 11x + 18 = 0 and x = 2 or x = 9. For x = 9 both sides equal 4, but for x = 2 the left side is 3 and the right side is −3, so 2 is an extraneous solution.
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Question 8
Which expression is equivalent to (8x6)2/3, where x > 0?
Correct answer: D
Raise each factor to the 2/3 power: 82/3 = (cube root of 8)2 = 22 = 4, and (x6)2/3 = x4. The choice 4x9 multiplies the exponent 6 by 3/2 instead of 2/3.
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Question 9
y = x2 − 2x + 1
y = x + 5The graphs of the equations shown intersect at two points in the xy-plane. If (a, b) is the intersection point with a > 0, what is the value of b?
Correct answer: C
Setting x2 − 2x + 1 = x + 5 gives x2 − 3x − 4 = 0, so x = 4 or x = −1. With a = 4, b = 4 + 5 = 9; the choice 4 is the value of a (and the y-value of the other point).
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Question 10
In the equation kx2 − 6x + 3 = 0, k is a constant. For which of the following values of k does the equation have no real solutions?
Correct answer: D
There are no real solutions when the discriminant is negative: (−6)2 − 4(k)(3) = 36 − 12k < 0, so k > 3. Only 4 works; k = 3 makes the discriminant 0, which gives exactly one solution.
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Question 11
The function f is defined by f(x) = 2(x − 3)2 + 5, and the function g is defined by g(x) = f(x + 4) − 1. What are the coordinates of the vertex of the graph of y = g(x) in the xy-plane?
Correct answer: A
Replacing x with x + 4 shifts the graph 4 units left, and subtracting 1 shifts it 1 unit down, so the vertex (3, 5) of f moves to (−1, 4). The choice (7, 4) shifts the graph right instead of left.
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