SAT Math : SAT Mathematics

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : Quadratic Equation

Solve for x: x2 + 4x = 5

Possible Answers:

None of the other answers

-5

-5 or 1

-1 or 5

-1

Correct answer:

-5 or 1

Explanation:

Solve by factoring.  First get everything into the form Ax2 + Bx + C = 0:

x2 + 4x - 5 = 0

Then factor: (x + 5) (x - 1) = 0

Solve each multiple separately for 0:

X + 5 = 0; x = -5

x - 1 = 0; x = 1

Therefore, x is either -5 or 1

Example Question #2 : Quadratic Equation

Solve for x: (x2 – x) / (x – 1) = 1

Possible Answers:

x = -2

x = 1

No solution

x = 2

x = -1

Correct answer:

No solution

Explanation:

Begin by multiplying both sides by (x – 1):

x2 – x = x – 1

Solve as a quadratic equation: x2 – 2x + 1 = 0

Factor the left: (x – 1)(x – 1) = 0

Therefore,  x = 1.

However, notice that in the original equation, a value of 1 for x would place a 0 in the denominator.  Therefore, there is no solution.

Example Question #4 : Quadratic Equation

A farmer has 44 feet of fence, and wants to fence in his sheep. He wants to build a rectangular pen with an area of 120 square feet. Which of the following is a possible dimension for a side of the fence? 

Possible Answers:

 

 

 

Correct answer:

Explanation:

Set up two equations from the given information:

\dpi{100} \small 120=xy and 

Substitute \dpi{100} \small y=\frac{120}{x} into the second equation:

Multiply through by \dpi{100} \small x.

Then divide by the coefficient of 2 to simplify your work:

Then since you have a quadratic setup, move the  term to the other side (via subtraction from both sides) to set everything equal to 0:

As you look for numbers that multiply to positive 120 and add to -22 so you can factor the quadratic, you might recognize that -12 and -10 fit the bill. This makes your factorization:

This makes the possible solutions 10 and 12. Since 12 does not appear in the choices, \dpi{100} \small 10\ feet is the only possible correct answer.

Example Question #2111 : Sat Mathematics

Find the roots of the following equation:

Possible Answers:

Correct answer:

Explanation:

The equation that is given can be factor into:

The roots is the locations where this equation equals zero as seen below:

This occurs when the value in either parenthesis equals zero.

Solving for the first expression:

Solving for the second root:

Therefore the roots are:

Example Question #34 : Quadratic Equations

Give the solution set of the equation 

Possible Answers:

The equation has no solution.

Correct answer:

Explanation:

The quadratic trinomial can be factored using the  method by looking for two integers whose sum is  and whose product is . Throught trial and error, we see that these integers are  and 8, so we continue:

One of the factors must be equal to 0, so either:

or 

The correct choice is .

Example Question #37 : Quadratic Equations

Consider the equation

.

Which of the following statements correctly describes its solution set?

Possible Answers:

Exactly two solutions, both of which are imaginary.

Exactly two solutions, both of which are irrational.

Exactly one solution, which is irrational.

Exactly one solution, which is rational.

Exactly two solutions, both of which are rational.

Correct answer:

Exactly two solutions, both of which are rational.

Explanation:

Write the quadratic equation in standard form  by subtracting  from both sides:

The nature of the solution set of a quadratic equation in standard form can be determined by examining the discriminant . Setting :

The discriminant is positive, so there are two real solutions. 

529 is a perfect square: 

.

Therefore, the two real solutions are also rational.

Example Question #36 : Quadratic Equations

Consider the equation

.

Which of the following statements correctly describes its solution set?

Possible Answers:

Exactly two solutions, both of which are rational.

Exactly one solution, which is irrational.

Exactly two solutions, both of which are irrational.

Exactly two solutions, both of which are imaginary.

Exactly one solution, which is rational.

Correct answer:

Exactly two solutions, both of which are imaginary.

Explanation:

Write the quadratic equation in standard form  by subtracting  from both sides:

The nature of the solution set of a quadratic equation in standard form can be determined by examining the discriminant . Setting :

The discriminant is negative, so there are two imaginary solutions. 

Example Question #27 : How To Find The Solution To A Quadratic Equation

Consider the equation

.

Which of the following statements correctly describes its solution set?

Possible Answers:

Exactly one solution, which is rational.

Exactly two solutions, both of which are imaginary.

Exactly two solutions, both of which are irrational.

Exactly one solution, which is irrational.

Exactly two solutions, both of which are rational.

Correct answer:

Exactly two solutions, both of which are irrational.

Explanation:

Write the quadratic equation in standard form  by subtracting 12 from both sides:

The nature of the solution set of a quadratic equation in standard form can be determined by examining the discriminant . Setting :

The discriminant is positive, so there are two real solutions. However, 145 is not a perfect square; the two solutions are therefore irrational.

Example Question #341 : Equations / Inequalities

Consider the equation:

 __________

Fill in the blank with a real constant to form an equation with exactly one real solution.

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

Explanation:

We will call the constant  that goes in the blank . The equation becomes

Write the quadratic equation in standard form  by subtracting  from both sides:

The solution set comprises exactly one rational solution if and only if the discriminant  is equal to 0. Setting . and substituting in the equation:

Solving for :

,

the correct response.

Example Question #342 : Equations / Inequalities

Consider the equation:

__________ 

Fill in the blank with a real constant to form an equation with exactly one real solution.

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

Explanation:

We will call the constant  that goes in the blank . The equation becomes 

Write the quadratic equation in standard form  by subtracting  from both sides:

The solution set comprises exactly one rational solution if and only if the discriminant  is equal to 0. Setting . and substituting in the equation:

Solving for :

,

the correct response.

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