Solve the Equation: Find the Missing Factor in 7 × ? = -21

Fill in the missing number:

7⋅?=−21 7\cdot?=-21

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:05 Let's figure out what the unknown is.
00:09 Remember, when you multiply a positive by a negative, you get a negative.
00:15 So, the unknown must be negative.
00:21 Now, we need to find this unknown value.
00:27 Here it is, let's make sure to add the negative sign.
00:31 And that's how we solve the problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Fill in the missing number:

7⋅?=−21 7\cdot?=-21

2

Step-by-step solution

Remember the following law:

(−x)×(+x)=−x (-x)\times(+x)=-x

Let's think about which number we need to multiply by 7 in order to get 21:

7×3=21 7\times3=21

Now let's put the numbers together with the appropriate sign as written in the law above as follows:

+7×(−3)=−21 +7\times(-3)=-21

3

Final Answer

−3 -3

Practice Quiz

Test your knowledge with interactive questions

What will be the sign of the result of the next exercise?

\( (-2)\cdot(-4)= \)

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