All Precalculus Resources
Example Questions
Example Question #91 : Graphing Functions
Find the distance between and
To find the distance, choose any point on one of the lines. Plugging in into the second equation can generate our first point:
this gives us the point
We can find the distance between this point and the other line by putting the second line into the form :
subtract the whole right side from both sides
multiply both sides by
now we see that
We can plug the coefficients and the point into the formula
where represents the point.
Example Question #11 : Distance
How far apart are the lines and ?
To find the distance, choose any point on one of the lines. Plugging in into the first equation can generate our first point:
this gives us the point
We can find the distance between this point and the other line by putting the second line into the form :
subtract the whole right side from both sides
multiply both sides by
now we see that
We can plug the coefficients and the point into the formula
where represents the point.
Example Question #31 : Calculus
Find the distance between and
To find the distance, choose any point on one of the lines. Plugging in into the second equation can generate our first point:
this gives us the point
We can find the distance between this point and the other line by putting the second line into the form :
subtract the whole right side from both sides
multiply both sides by
now we see that
We can plug the coefficients and the point into the formula
where represents the point.
Example Question #2 : Find The Distance Between Two Parallel Lines
Find the distance between and
To find the distance, choose any point on one of the lines. Plugging in into the first equation can generate our first point:
this gives us the point
We can find the distance between this point and the other line by putting the second line into the form :
subtract the whole right side from both sides
multiply both sides by
now we see that
We can plug the coefficients and the point into the formula
where represents the point.
Example Question #31 : Gre Subject Test: Math
Find the distance between the lines and
To find the distance, choose any point on one of the lines. Plugging in into the first equation can generate our first point:
this gives us the point
We can find the distance between this point and the other line by putting the second line into the form :
subtract the whole right side from both sides
multiply both sides by
now we see that
We can plug the coefficients and the point into the formula
where represents the point.
Example Question #1 : Find Roots Of Quadratic Equation Using Discriminant
True or false: for a quadratic function of form ax2 + bx + c = 0, if the discriminant b2 - 4ac = 0, there is exactly one real root.
True
False
True
This is true. The discriminant b2 - 4ac is the part of the quadratic formula that lives inside of a square root function. As you plug in the constants a, b, and c into b2 - 4ac and evaluate, three cases can happen:
b2 - 4ac > 0
b2 - 4ac = 0
b2 - 4ac < 0
In the first case, having a positive number under a square root function will yield a result that is a positive number answer. However, because the quadratic function includes , this scenario yields two real results.
In the middle case (the case of our example), . Going back to the quadratic formula , you can see that when everything under the square root is simply 0, then you get only , which is why you have exactly one real root.
For the final case, if b2 - 4ac < 0, that means you have a negative number under a square root. This means that you will not have any real roots of the equation; however, you will have exactly two imaginary roots of the equation.
Example Question #2 : Find Roots Of Quadratic Equation Using Discriminant
True or false: for a quadratic function of form ax2 + bx + c = 0, if the discriminant b2 - 4ac > 0, there are exactly 2 distinct real roots of the equation.
True
False
True
This is true. The discriminant b2 - 4ac is the part of the quadratic formula that lives inside of a square root function. As you plug in the constants a, b, and c into b2 - 4ac and evaluate, three cases can happen:
b2 - 4ac > 0
b2 - 4ac = 0
b2 - 4ac < 0
In the first case (the case of our example), having a positive number under a square root function will yield a result that is a positive number answer. However, because the quadratic function includes , this scenario yields two real results.
In the middle case, . Going back to the quadratic formula , you can see that when everything under the square root is simply 0, then you get only , which is why you have exactly one real root.
For the final case, if b2 - 4ac < 0, that means you have a negative number under a square root. This means that you will not have any real roots of the equation; however, you will have exactly two imaginary roots of the equation.
Example Question #3 : Find Roots Of Quadratic Equation Using Discriminant
True or false: for a quadratic function of form ax2 + bx + c = 0, if the discriminant b2 - 4ac < 0, there are exactly two distinct real roots.
True
False
False
This is false. The discriminant b2 - 4ac is the part of the quadratic formula that lives inside of a square root function. As you plug in the constants a, b, and c into b2 - 4ac and evaluate, three cases can happen:
b2 - 4ac > 0
b2 - 4ac = 0
b2 - 4ac < 0
In the first case, having a positive number under a square root function will yield a result that is a positive number answer. However, because the quadratic function includes , this scenario yields two real results.
In the middle case, . Going back to the quadratic formula , you can see that when everything under the square root is simply 0, then you get only , which is why you have exactly one real root.
For the final case (the case of our example), if b2 - 4ac < 0, that means you have a negative number under a square root. This means that you will not have any real roots of the equation; however, you will have exactly two imaginary roots of the equation.
Example Question #1 : Find Roots Of Quadratic Equation Using Discriminant
Use the formula b2 - 4ac to find the discriminant of the following equation: 4x2 + 19x - 5 = 0.
Then state how many roots it has, and whether they are real or imaginary. Finally, use the quadratic function to find the exact roots of the equation.
Discriminant: 0
One real root:
Discriminant: 281
Two imaginary roots:
Discriminant: 441
Two real roots: or
Discriminant: 441
Two real roots: or
Discriminant: 281
Two imaginary roots:
Discriminant: 441
Two real roots: or
In the above equation, a = 4, b = 19, and c = -5. Therefore:
b2 - 4ac = (19)2 - 4(4)(-5) = 361 + 80 = 441.
When the discriminant is greater than 0, there are two distinct real roots. When the discriminant is equal to 0, there is exactly one real root. When the discriminant is less than zero, there are no real roots, but there are exactly two distinct imaginary roots. In this case, we have two real roots.
Finally, we use the quadratic function to find these exact roots. The quadratic function is:
Plugging in our values of a, b, and c, we get:
This simplifies to:
which simplifies to
which gives us two answers:
or
These values of x are the two distinct real roots of the given equation.
Example Question #2 : Find Roots Of Quadratic Equation Using Discriminant
Use the formula b2 - 4ac to find the discriminant of the following equation: 4x2 + 12x + 10 = 0.
Then state how many roots it has, and whether they are real or imaginary. Finally, use the quadratic function to find the exact roots of the equation.
Discriminant: 304
Types of Roots: Two distinct real roots
Exact Roots:
Discriminant: 304
Types of Roots: Two distinct real roots
Exact Roots:
Discriminant: -16
Types of Roots: No real roots; 2 distinct imaginary roots
Exact Roots:
Discriminant: -16
Types of Roots: No real roots; 2 distinct imaginary roots
Exact Roots:
Discriminant: 16
Types of Roots: Two distinct real roots
Exact Roots: -1, -2
Discriminant: -16
Types of Roots: No real roots; 2 distinct imaginary roots
Exact Roots:
In the above equation, a = 4, b = 12, and c = 10. Therefore:
b2 - 4ac = (12)2 - 4(4)(10) = 144 - 160 = -16.
When the discriminant is greater than 0, there are two distinct real roots. When the discriminant is equal to 0, there is exactly one real root. When the discriminant is less than zero, there are no real roots, but there are exactly two distinct imaginary roots. In this case, we have two distinct imaginary roots.
Finally, we use the quadratic function to find these exact roots. The quadratic function is:
Plugging in our values of a, b, and c, we get:
This simplifies to:
In other words, our two distinct imaginary roots are and
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