Answer:
30
Step-by-step explanation:
For a = <xa, ya> and b = <xb, yb>, the dot product is the sum of products ...
a·b = (xa)(xb) + (ya)(yb)
Substituting the given information, you have ...
a·b = 5·4 + 2·5 = 20 + 10
a·b = 30
_____
Some graphing calculators can do such math. There are also dot product calculators available on the Internet. If you have quite a few of these to calculate, you can put the appropriate formula into a spreadsheet.
Answer:
.
Step-by-step explanation:
We want to convert the function into the form that let's us easily find the x-intercept, and it would be for the form
because then we can find the x-intercept in the following manner:



We factor our function
and get

Now this form let's us easily find the x-intercepts:


and so we pick the second choice: f(x)=(2x+1)(2x-1).
Answer
Find out the how long did they rest in 8 hours.
To prove
As given
contestants in a dance-a-thon rest for the same amount of time every hour.
A couple rests for 25 minutes in 5 hours .
As
25 mintues = 5 hours

1 hours = 5 mintues
Thus in 1hours a the dance -a-thon rest for 5 mintues.
Now for 8 hours.
8 hours = 8 × 5 mintues
= 40 mintues
Therefore in 8 hours a dance-a-thon rest for 40 mintues.