Solving One-Step Equations 03:04 minutes

Video Transcript

Transcript Solving One-Step Equations

Today, something happened at the zoo. Some baby lions have run away. There are only 2 out of 7 baby lions left in the cage. How many baby lions do the zookeepers need to catch?

One-step Equations Example 1

To solve this we can use a one-step equation with a variable. Let x represent the number of missing baby lions. To this we can add the 2 that did not escape. This equals 7, which is the total number of baby lions in the zoo.

An equation is like a scale. On the left side of the scale, you have a box for the number of missing baby lions, which are represented by x. In addition, you have 2 baby lions that are remaining. On the right side of the scale, you have the total of 7 baby lions in the zoo.

Now, the scale is in balance. If you take one lion baby away from the left side of the scale, the scale becomes unbalanced. So, you have to take away the same amount, one lion, from the other side. This gets the scale back in balance.

If you take away one more baby lion from the left side, and you take away one more from the right side, you see the box for the missing baby lions is equal to 5. So, there are 5 baby lions missing.

Solving an one-step Equation algebraically

This is basically how equations work. Keep the scale in mind when you solve an equation algebraically.

Our goal here is to isolate x. To get rid of the plus 2 on the left side of the equation, we use the opposite operation. In this case, the opposite of adding 2 is subtracting 2.

Remember our scale. What you do to one side of the equation, you have to do to the other side of the equation. So, we take away 2 from the right side of the equation as well: x + 2 − 2 = x on the left side, 7 − 2 = 5 on the right side. So, our equation now says x = 5.

One-step Equations Example 2

Let's look at another example. The equation is 3 times x = 30. To isolate the x, you use the opposite operation. The opposite operation of multiplying is dividing. So, in this case we divide by 3.

Remember that what you do to one side of the equation, you have to do to the other side of the equation, so we divide this side by 3 as well: 3 · x ÷ 3 = x and 30 ÷ 3 = 10 on the right side. So, our equation now says x = 10.

Rules how to solve one-step Equations

So remember:

  • To isolate x, use the opposite operation again.
  • The opposite operations of addition is always subtraction and vice versa.
  • The opposite operation of multiplication is always division and vice versa.
  • What you do to one side, you have to do to the other side.

Let's get back to the baby lions. It is already 5 o’clock and 4 out of the 5 missing baby lions are back, but one is still missing.

Look! what is happening in the snake house? It seems like our baby lion is in trouble – phew, its just the British tea snake.

2 comments
  1. Julia redaktion

    Hi @Mcweinman2134, I guess you write about question number 3 in the interactive practice problems?
    This is a drag&drop question type. The words and formulas to fill in the blanks are in a box below. To check your answer please scroll down and press the button "check answer". Then you get a feedback if it's right or wrong. You have 3 tries to answer every question. In the offline version of the worksheets you find all solutions on the last pages of the pdf.

    I hope I could help.
    Julia

    Posted by Julia Merck, over 1 year ago
  2. Default

    hey there: where/how do I fill in the blanks on the Homework sheets? and how do do I check them? you are not very organized in some lessons do I need a PDF? to work this?

    Posted by Mcweinman2134, over 1 year ago