In which special cases does the scalar product of a vector satisfy the law of association I only know that a · (B · C) = (a · b) · C holds when all three vectors are zero vectors. Is there any other case? | Math enthusiast | Mathematical art

In which special cases does the scalar product of a vector satisfy the law of association I only know that a · (B · C) = (a · b) · C holds when all three vectors are zero vectors. Is there any other case?

A · (B · C) = (a · b) · C is improper. It should be a (B · C) = (a · b) C. [· is the scalar product of vector, and "concatenation" is the multiplication (multiplication) of number and vector]. If the above formula is true, it needs ① a ‖ C, ② a, C in the same direction, | a × (B · C) = (a · b) × | C |. A, C in the opposite direction, | a × (B · C) = -

85 * 99 + 99 help me with combination law, distribution rate or exchange law

85*（100-1）+99=8500-85+99=8514

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