Answer:
commutative property of multiplication
Explanation:
You want to know the property of multiplication that lets you rewrite (6+x)x as x(6+x).
Commutative property
When an operation has the commutative property, it means the order in which the two operands appear can be changed (reversed) without affecting the result of the operation.
Here, you have a multiplication expression with operands (6+x) and x. They are first written in the order ...
(6+x) · x
and then reversed to the order ...
x · (6+x)
The property of multiplication that lets you do that without changing the result is the commutative property of multiplication.
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Additional comment
Multiplication of some kinds of operands does not have the commutative property. In general, a vector cross product, and a matrix product will produce different results when the operands are reversed.