Simplify the Expression: x-(3x+4y) Using Algebraic Properties

Distributive Property with Negative Signs

x(3x+4y)=? x-(3x+4y)=\text{?}

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Step-by-step video solution

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00:00 Solve
00:03 Note, when multiplying negative by positive it's always negative
00:14 Collect terms
00:19 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

x(3x+4y)=? x-(3x+4y)=\text{?}

2

Step-by-step solution

First, we open the parentheses and change the sign accordingly.

Since there are only positive numbers within the parentheses, multiplying by a negative will give us negative numbers:

x3x4y= x-3x-4y=

Now we group the X factors:

x3x=2x x-3x=-2x

We obtain:

2x4y -2x-4y

3

Final Answer

2x4y -2x-4y

Key Points to Remember

Essential concepts to master this topic
  • Distribution Rule: Negative sign multiplies every term inside parentheses
  • Technique: x-(3x+4y) becomes x-3x-4y by distributing the minus
  • Check: Substitute values: if x=1, y=2, then 1-(3+8)=-10, and -2-8=-10 ✓

Common Mistakes

Avoid these frequent errors
  • Not changing signs of all terms when distributing
    Don't keep x-(3x+4y) = x-3x+4y with positive 4y! The negative distributes to both 3x AND 4y, making both terms negative. Always change the sign of every term inside the parentheses when distributing a negative.

Practice Quiz

Test your knowledge with interactive questions

\( 70:(14\times5)= \)

FAQ

Everything you need to know about this question

Why does the 4y become negative when there's no minus sign in front of it?

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The negative sign in front of the parentheses acts like multiplying by -1. Since 1×(+4y)=4y -1 \times (+4y) = -4y , the 4y becomes negative even though it was positive inside.

What's the difference between x-3x+4y and x-(3x+4y)?

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The parentheses make a huge difference! x-3x+4y gives you 2x+4y -2x+4y , but x-(3x+4y) gives you 2x4y -2x-4y . The parentheses change the sign of everything inside.

How do I remember to distribute the negative to all terms?

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Think of the negative as -1 multiplying the entire expression. Write it as x+(1)(3x+4y) x + (-1)(3x+4y) to see that -1 multiplies both 3x and 4y!

Can I check my answer by plugging in numbers?

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Absolutely! Try x=2, y=1. Original: 2(32+41)=210=8 2-(3 \cdot 2+4 \cdot 1) = 2-10 = -8 . Your answer: 2(2)4(1)=44=8 -2(2)-4(1) = -4-4 = -8

What if there are more terms inside the parentheses?

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The same rule applies! The negative sign distributes to every single term inside the parentheses, no matter how many there are. Each positive becomes negative, and each negative becomes positive.

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