-2x+y=5
x-3y=-30 so you can multiply the bottom equation by 2 you'll get 2x-6y=-60
-2x+y=5
2x-6y=-60 And subtract the equations. You'll get -5y=-55 y=11. Plug it in to one of the original equations. -2x+(11)=5
-2x=-6 so x=3
y=11 and x=3
Answer:
Option C. 
Step-by-step explanation:
we know that
Using a Excel tool (Correl function)
see the attached table
The r-value is
Simple use the cuboid volume formula for each of them
The answer is Tuesday there will be 15 teachers for 179 students and 12 times 15 is 180
For cos(2x) * (2cos(x) + 1) = 0, use the double angle identity for cos(2x), which is cos^2 x - sin^2 x = cos^2 x - (1-cos^2) = 2cos^2 x - 1.
So we have (2cos^2 x - 1)(2cos x + 1) = 0. So 2cos^2 x -1 = 0 or x = 0 and 2pi.
For 2sec^2 x + tan^2 x - 3 = 0, use the identity sec^2 x = tan^2 x + 1, so we have
2(tan^2 x + 1) + tan^2 x - 3 = 0 or
<span>2tan^2 x + tan^2 x - 1 = 0 or
</span>3 tan^2 x = 1.
So x = pi/2, pi/2 + pi = 3pi/2.
