(2n + 5k)^2 = (2n + 5k)(2n + 5k)
Here we need to use FOIL
First - 2n * 2n = 4n^2
Outside - 2n * 5k = 10nk
Inside - 5k * 2n = 10nk
Last - 5k * 5k = 25k^2
That gives us 4n^2 + 10nk + 10nk + 25k^2, we can combine 10nk + 10nk to give 20nk, and a final equaion of 4n^2 + 20nk + 25k^2
Answer:

Step-by-step explanation:
Cosine is the adjacent side over the hypotenuse (You can remember sin, cos, and tan by using sohcahtoa or sin = opposite/hypotenuse, cos = adjacent/hypotenuse, tan = opposite over adjacent). I think a picture would help, too.
I attached a picture of what I think the triangle would look like.
If the picture is right (we're assuming it is) and going with what we're given (the triangle was addressed as triangle XYZ, meaning that <u>angle Y is in the middle and that's the one we'll use</u>).
Looking at my picture then:
.
21.
a. Ratio of blue: green
Length blue: length green
3:6 or 1:2
Width blue :width green
2:4 or 1:2
Perimeter blue: perimeter green
2+2+3+3=10: 4+4+6+6= 20 or 1 :2
Area blue: Area green
2•3=6 : 4•6= 24 or 1:4
b. The lenght, with and perimeter of the big green rectangle are double the size of the small blue rectangle.
The area of the big green rectangle is 4 times greater than the area of the small blue rectangle. So if the lenghts of a rectangle are doubled the perimeter is doubled and the area is 4 times biger than the area of the doubeled rectangle.
The answer is d. i hate how you have to have 20 words
Answer:
(1,6) is not a solution and I think the second one is: c I think
Step-by-step explanation: