How do you use cross products to solve #3/x=4/28#?

2 Answers
Jan 26, 2017

Answer:

#x=21#

Explanation:

#color(blue)(3)/color(red)(x)=color(red)(4)/color(blue)(28)#

Now multiply the #color(red)"values in red"# together, the #color(blue)"values in blue"# together and equate them.

As you can see, this multiplication forms a cross (X) hence the reason it is called cross products.

#rArrcolor(red)(4x)=(color(blue)(3)xxcolor(blue)(28))#

#rArr4x=84#

To solve for x, divide both sides by 4

#(cancel(4) x)/cancel(4)=84/4#

#rArrx=21#

#color(blue)"As a check"#

substitute this value into the equation and if the left side equals the right side for this value then it is the solution.

#"left side "=3/21=cancel(3)^1/cancel(21)^7=1/7#

#"right side "=4/28=cancel(4)^1/cancel(28)^7=1/7#

#rArrx=21" is the solution"#

Jan 26, 2017

Answer:

#x=21#

Explanation:

#3/x = 4/28#

#3/x = 1/7#

Cross multiply:

#x xx1 = 3xx7#

#x=21#