ShmoopTube

Where Monty Python meets your 10th grade teacher.

Search Thousands of Shmoop Videos

CAHSEE Math 1.3 Mathematical Reasoning 183 Views


Share It!


Description:

CAHSEE Math Mathematical Reasoning: Drill 1 Problem 3. Which of the following is the correct order of steps?

Language:
English Language

Transcript

00:03

You look too happy. Here’s an unshmoopy question to take you down a peg…

00:08

When solving the equation one over x minus one-half equals 3 for x,

00:13

which of the following is the correct order of steps?

00:16

And here are the potential answers...

00:20

OK, so this question is just pushing us to think about patterns of problem solving…

00:25

and it throws in some curves and freebies as well.

00:29

Note that potential answer B asks about SUBTRACTING a half from both sides – well, since our

00:35

one-half on the left is already negative, we wouldn’t be able to cancel it out.

00:40

It would just be useless so we can eliminate option B right away.

00:43

Consider just the remaining 3 – and remember that the key goal in solving any of these

00:47

kinds of problems is to isolate x.

00:50

If we add a half to both sides – which is the first thing we do in the other potential

00:54

answers – the new equation looks like this:

00:57

1 over x equals 3 plus one-half.

01:01

So the next step is to just simplify 3 PLUS 1 half to be uh, yeah – 3 and a half.

01:08

Note that C has you subtracting a half as the second step here – and that’s just wrong –

01:13

we’ve ADDED a half to both sides; so you can cross out C.

01:17

So it gets down to D versus A.

01:21

A suggests taking the RECIPROCAL of the result whereas D asks us to take the OPPOSITE of the result.

01:28

The… opposite of the result? Not even sure what that would be. Sounds like someone who

01:32

just landed on our planet and is trying to fit in.

01:35

Taking the RECIPROCAL, however, makes sense.

01:37

Since we have 1 over x on the left side of the equation,

01:40

we can simply flip both sides to get x on the left…

01:44

…and one over 3 and a half on the right… which is 1 over 7 halves… or two-sevenths.

01:50

A it is.

01:51

As in… “Alien mathletes.”

Up Next

CAHSEE Math 5.3 Algebra and Functions
2032 Views

CAHSEE Math: Algebra and Functions Drill 5, Problem 3. Solve the equation.

Related Videos

Simplifying Radicals
9737 Views

We don't like knocking people down to size, but we do like simplifying radicals. Join us?

Arithmetic Math
2248 Views

If fleeing criminals always fled the scene of the crime at perfect right angles, it would be much easier to determine their whereabouts. Fortunatel...

Basics of Game Theory
882 Views

Okay, so this probably isn't going to help you master Pokemon Go, but game theory can be applied to all sorts of situations. Even stomping your old...