Question

how do you do cross product

Answer 1

Better shown by example. As a specific question with numbers and such.

Answer 2

3/4=15/20

Answer 3

3*20=15*4

Answer 4

so thats it

Answer 5

Are you talking about cross multiply algebra, or cross vector calculus?

Answer 6

He's talking about algebra.

Answer 7

\[{x \over 4} = {15 \over 20}\]
\[\implies ({20 \times 4}) {x \over 4} = ({20 \times 4}) {15 \over 20}\]
\[\implies 20x =4(15) \implies 20x = 60 \implies x = 3\]

Answer 8

All you're doing is multiplying both sides by the product of the two denominators.

Answer 9

Since each side is over one of the two denominators that will cancel with one of the factors in your product.