SAT Math : How to find f(x)

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1121 : Algebra

Solve for .

Possible Answers:

Correct answer:

Explanation:

Multiply by  on each side

Expand right side

Subtract  on each side

Divide by  on each side

Example Question #1122 : Algebra

If a rocket is shot from the ground, and it takes  to reach a height of . Determine the equation of its trajectory.

Possible Answers:

Correct answer:

Explanation:

To figure out what the equation is, we need to use the point-slope form.

, where  is the slope, and  is a point.

In this example, 

Example Question #1121 : Algebra

Screen shot 2016 02 18 at 1.42.15 pm

Determine the x-intercepts in the graph above.

Possible Answers:

Not enough information

Correct answer:

Explanation:

The x-intercepts are the points on the graph where the  line touches or intersects the x axis. By looking at the graph, there are two points. One at , and then another one at . So there are two x intercepts. 

Example Question #1124 : Algebra

Stuff animals were a strange craze of the 90's. A Cat stuff animal with white paws sold for $6 in 1997. In 2015, the Cat will sell for $1015. What has been the approximate rate of growth for these stuff animal felines?

Possible Answers:

Correct answer:

Explanation:

Use the formula for exponential growth where y is the current value, A is the initial value, r is the rate of growth, and t is time. Between 1997 and 2015, 18 years passed, so use . The stuffed animal was originally worth $6, so . It is now worth $1,015, so .

Our equation is now:

divide by 6:

take both sides to the power of :

subtract 1

As a percent, r is about 33%.

 

Example Question #1121 : Algebra

The population of a city will decrease by 15 percent every 50 years and the population starts at 120,000 people. Construct a function that describes this situation.

Possible Answers:

Correct answer:

Explanation:

To construct a function that describes this situation first identify what is known.

Since this particular situation is talking about population decrease, the function will be an exponential decay.

Recall that an exponential decay function is in the form,

 

where,

Since the statements says that the population decreases every 50 years we can rewrite the general form to,

Now substituting in the known values, the function can be written. 

Example Question #1126 : Algebra

Screen shot 2016 02 18 at 2.50.12 pm

The above graph shows supply and demand for a particular Product. What is the equation for the demand of this product?

Possible Answers:

Correct answer:

Explanation:

We can determine the demand equation by using point slope form.

Point slope form is , where , and  is the slope, where .

Let , and .

Now we have

Choose a point ,

Example Question #1127 : Algebra

Screen shot 2016 02 18 at 2.50.12 pm

If the equation of the demand line is , and the equation for supply is , determine the point where supply and demand is the same.

Possible Answers:

Correct answer:

Explanation:

To solve this, all we need to do is set the equations equal to each other.

Now solve for 

Example Question #1128 : Algebra

Amanda has  ants in an ant farm and their population grows  annually. How many ants will be in Amanda's ant farm in 6 years?

Possible Answers:

Correct answer:

Explanation:

This is an exponential growth problem, so let's recall the equation for exponential growth.

, where  is the starting amount of ants,  is the growth rate, and  is the time in years.

First step is to convert  into a decimal. 

So in 6 years, Amanda will have  ants.

 

Example Question #1129 : Algebra

The equation for the universal gravitation is , and  is the universal gravitational constant. If , and , what is the radius between the two masses? Round to the nearest tenth.

Hint: 

Possible Answers:

Correct answer:

Explanation:

The first step is to plug in all the values into the equation.

Now we will solve for .

 

 

Take the square root on each side

 

Example Question #11 : Algebraic Functions

If , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

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