ShmoopTube

Where Monty Python meets your 10th grade teacher.

Search Thousands of Shmoop Videos


Pre-Algebra Videos 217 videos

Compound Interest
45304 Views

Who wants to be a millionaire? In this video, learn about compound interest, interest rates, and the compound interest formula. You'll be buying th...

ACT Math 5.2 Pre-Algebra
1939 Views

ACT Math: Pre-Algebra Drill 5, Problem 2. If a and b are prime numbers, how many factors does ab have?

SAT Math 4.3 Numbers and Operations
2174 Views

SAT Math 4.3 Numbers and Operations

See All

SAT Math 7.3 Algebra and Functions 318 Views


Share It!


Description:

SAT Math 7.3 Algebra and Functions

Language:
English Language

Transcript

00:02

Here's your shmoop du jour, brought to you by parametric equations.

00:07

Which have nothing to do with EMTs, ambulances or blood transfusions you read about.

00:12

Thank goodness.

00:13

If x = t + 1 and y = 3t squared + 2t - 1,

00:18

then y is also equal to which of the following?

00:21

And here are the potential answers...

00:26

See those t's in the x and y equations?

00:28

This shows us that we're dealing with something

00:31

called PARAMETRIC equations.

00:33

It's basically where we write our x and y equations in terms of another variable...like t.

00:41

This question asks us to solve for y...if we look at our answer choices, they want us

00:45

to solve for y in terms of x.

00:48

Well, we can do this by solving for t in terms of x and then substituting

00:51

the t value in terms of x back into the y equation.

00:55

Rearranging the first equation so that  t is by itself on one side...

01:00

we get t equals x - 1.

01:02

We can just insert x - 1 into the equation now wherever we see t...

01:08

x - 1 squared is the same as x - 1 times x - 1...

01:14

...which equals x squared - x - x + 1.

01:20

When we add like terms, we get x squared - 2x + 1.

01:27

That value times 3...gives us 3x squared - 6x + 3.

01:31

2 times the quantity x - 1 equals 2x - 2...

01:37

Combining like terms...we have 3x squared - 6x + 2x

01:42

and that gives us - 4x...3 - 2 - 1...gives us 0.

01:49

So we're left with 3x squared - 4x.

01:51

Which is answer choice (C).

Related Videos

SAT Math 2.1 Geometry and Measurement
2779 Views

SAT Math 2.1 Geometry and Measurement. What is the measure of angle z in terms of x and y?

SAT Math 9.4 Algebra and Functions
1300 Views

SAT Math 9.4 Algebra and Functions

SAT Math 9.2 Algebra and Functions
377 Views

SAT Math 9.2 Algebra and Functions

SAT Math: Identifying an Equation for the Average of Two Percentages
23 Views

In 2014, the unemployment rate of one county in California was 7%. In another county, the unemployment rate was 11%. Which of the following express...

SAT Math: Which Equation Represents Profit?
13 Views

Angela is making cookies for a bake sale. She expects each batch of her cookies to sell for $40. It costs her $10 to make one batch of cookies, and...