Math  /  Algebra

QuestionQuestion 7 (1 point) Solve for x 1/3x=3/4-1 / 3 x=3 / 4 1/41 / 4 21/4-21 / 4 1/4-1 / 4 13/413 / 4

Studdy Solution

STEP 1

What is this asking? We need to find the value of xx that makes 1/3x-1/3x equal to 3/43/4. Watch out! Don't forget to be careful with those negative signs, they can be sneaky!

STEP 2

1. Isolate xx
2. Simplify

STEP 3

We want to get rid of that 1/3-1/3 attached to the xx.
To do this, we can multiply both sides of the equation by **3**.
Remember, whatever we do to one side, we *must* do to the other to keep the equation balanced!
This is like a seesaw, we want to keep it level! 1/3x=3/4-1/3 \cdot x = 3/4 (1/3x)3=(3/4)3(-1/3 \cdot x) \cdot 3 = (3/4) \cdot 3

STEP 4

On the left side, the **3** and **1/3** multiply to **one**, leaving us with 1x-1 \cdot x or just x-x.
On the right side, we have (3/4)3=9/4(3/4) \cdot 3 = 9/4.
So now our equation looks like this: x=9/4-x = 9/4

STEP 5

We're so close!
We want xx, not x-x.
Let's multiply both sides by 1-1.
This will flip the sign on both sides: (x)(1)=(9/4)(1)(-x) \cdot (-1) = (9/4) \cdot (-1)

STEP 6

A negative times a negative is a positive, and a positive times a negative is a negative.
So, we have: x=9/4x = -9/4

STEP 7

We can rewrite 9/4-9/4 as a mixed number.
How many times does **4** go into **9**?
It goes in **2** times with a remainder of **1**.
So, 9/4-9/4 is the same as 2 1/4-2\ 1/4. 9/4=2 1/4-9/4 = -2\ 1/4

STEP 8

So, x=9/4x = -9/4 or x=2 1/4x = -2\ 1/4.
Looking back at the choices, 2 1/4-2\ 1/4 is the same as 2.25-2.25, which isn't listed, but 9/4-9/4 can be written as 2 1/4-2\ 1/4, which is equivalent to 2+(1/4)-2 + (-1/4), which simplifies to 21/4-2 - 1/4, which is written as 2 1/4-2\ 1/4, which is the same as 214-2\frac{1}{4}.

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