I think it’s D) 9 because when you find the mean of a set of values you are taking into account and adding all of the numbers, and then dividing them by how many numbers there is, so the mean would be summarizing all of them, hope this helps

5 0

2 years ago

Planes X and Y are perpendicular. Points A, E, F, and G are points only in plane X. Points R and S are points in both planes X a

marusya05 [52]

Answer:

Planes EA and FG

Step-by-step explanation:

3 0

3 years ago

Please help!!

yarga [219]

Because this is a fourth degree that will be tricky to factor as it is, we will do a u substitution. Let $x^2=u$ . We can now rewrite that polynomial in terms of u: $u^2-7u-8=0$ . Filling into the quadratic formula we have $u=\frac{7+/-\sqrt{49-4(1)(-8)}}{2}$ . Simplifying down $u=\frac{7+/-\sqrt{81}}{2}$ and $u=\frac{7+9}{2}$ or $u=\frac{7-9}{2}$ . That means that u = 8 or u = -1. But don't forget that we let $u=x^2$ , so we have to put x-squared back in for u. That gives us $x^2=8$ which simplifies down to $+/-2\sqrt{2}$ . That also gives us $x^2=-1$ . When we take the square root of -1, we have to use the fact that -1 = i^2, so we sub that in to get $x=+/-i$ . All in all, your solutions are as follows: $2\sqrt{2},-2\sqrt{2},i,-i$ which is choice b.