## anonymous 5 years ago how do you do cross product

1. anonymous

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

2. anonymous

3/4=15/20

3. anonymous

3*20=15*4

4. anonymous

so thats it

5. anonymous

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

6. anonymous

7. anonymous

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

8. anonymous

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

9. anonymous

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