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The Distributive Property

The distributive property says that multiplying a sum is the same as multiplying each piece and then adding: a(b+c)=ab+aca(b + c) = ab + ac. In practice, it's the rule for clearing parentheses — the number outside multiplies each term inside, not just the first one.

It's one of the most-used moves in all of algebra. You need it to simplify expressions like 3(x+5)3(x + 5), to solve equations that have parentheses, and later to multiply polynomials. Learn to distribute cleanly — especially with negative signs — and a whole category of mistakes disappears.

What the property says

In 3(x+5)3(x + 5), the 33 multiplies each term inside the parentheses: 3x=3x3 \cdot x = 3x and 35=153 \cdot 5 = 15, so 3(x+5)=3x+153(x + 5) = 3x + 15. Every term inside gets its own multiplication — the most common error is multiplying only the first term and writing 3x+53x + 5.

You can see why it works with plain numbers. 3(10+2)3(10 + 2) is 312=363 \cdot 12 = 36, and distributing gives 30+6=3630 + 6 = 36 — same answer. Three groups of x+5x + 5 really is three xx's plus three 55's.

Negatives and subtraction

The sign travels with the number. In 2(x4)-2(x - 4), you distribute 2-2 to each term: 2x=2x-2 \cdot x = -2x and 2(4)=+8-2 \cdot (-4) = +8, so 2(x4)=2x+8-2(x - 4) = -2x + 8. A negative times a negative is positive, and this is exactly where students drop that rule under pressure.

Subtraction inside the parentheses works the same way — treat x4x - 4 as x+(4)x + (-4) and multiply each term, sign included. When the outside number is negative, expect every sign inside to flip.

Distribute first, then combine like terms

Distributing usually isn't the last step. In 3(x+2)+5x3(x + 2) + 5x, distribute to get 3x+6+5x3x + 6 + 5x, then combine the like terms 3x3x and 5x5x to finish with 8x+68x + 6. The order is always the same: clear the parentheses first, then combine whatever matches.

Worked examples

Example 1: a positive number outside

Distribute 4(x+6)4(x + 6).

Start with the expression4(x+6)4(x + 6)
Multiply 44 by the first term4x=4x4 \cdot x = 4x
Multiply 44 by the second term46=244 \cdot 6 = 24
Add the pieces4x+244x + 24

Answer: 4x+244x + 24

Example 2: subtraction inside

Distribute 7(2y3)7(2y - 3).

Start with the expression7(2y3)7(2y - 3)
Multiply 77 by the first term72y=14y7 \cdot 2y = 14y
Multiply 77 by the second term, keeping its sign7(3)=217 \cdot (-3) = -21
Put the pieces together14y2114y - 21

Answer: 14y2114y - 21

Example 3: a negative number outside

Distribute 3(5x+2)-3(5x + 2).

Start with the expression3(5x+2)-3(5x + 2)
Multiply 3-3 by the first term35x=15x-3 \cdot 5x = -15x
Multiply 3-3 by the second term32=6-3 \cdot 2 = -6
Put the pieces together15x6-15x - 6

Answer: 15x6-15x - 6

Example 4: distribute, then combine like terms

Simplify 3(x+2)+5x3(x + 2) + 5x.

Start with the expression3(x+2)+5x3(x + 2) + 5x
Distribute the 333x+6+5x3x + 6 + 5x
Combine the like terms 3x3x and 5x5x8x+68x + 6

Answer: 8x+68x + 6

Try one yourself

Common questions

Do I multiply every term inside the parentheses, or just the first one?

Every term. 3(x+5)3(x + 5) is 3x+153x + 15, not 3x+53x + 5. If there are three terms inside, the outside number multiplies all three. Stopping after the first term is the single most common distributing mistake.

What happens when the number outside is negative?

The negative distributes too, so every sign inside flips. 2(x4)=2x+8-2(x - 4) = -2x + 8: the 2-2 times xx gives 2x-2x, and the 2-2 times 4-4 gives +8+8. Check each product's sign one at a time.

Does it work if the number is behind the parentheses, like (x+3)4(x + 3) \cdot 4?

Yes. Multiplication works in either order, so (x+3)4=4(x+3)=4x+12(x + 3) \cdot 4 = 4(x + 3) = 4x + 12. The multiplier distributes to each term no matter which side it sits on.

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