Answer:
15
Step-by-step explanation:
distance formula




15
Answer:
2/10 or 1/5 if you want it simplified
Step-by-step explanation:
9/10 is basically 9 and 7/10 is 7 so 9 - 7 is 2 and we need to add the /10 back so it's 2/10 or 1/5
The <em>correct answer</em> is:
D) reflect over the y axis and then reflect again over the y axis.
Explanation:
Logically, if we reflect a figure across the y-axis and then reflect across the y-axis again, we have undone what we originally did, and the figure is back in its original position.
Algebraically, reflecting across the y-axis maps every point (x, y) to (-x, y). Reflecting this point across the y-axis maps (-x, y) to (x, y); this is our original point.
(a-b) X (a+b)
= aXa - bXa +aXb -bXb (distributing)
Now, cross product of a vector with itself = 0
so, aXa = 0, bXb = 0
Also, aXb = - bXa
so,
(a-b) X (a+b) = 0 + aXb + aXb + 0
= 2aXb
hence, proved :)