Answer:
x = pi/2, 3pi/2 x = pi
Step-by-step explanation:
cos2x + 2 cos x + 1 = 0
cos 2x = cos^2 - sin^2x trig identity
cos^2x -sin^2 + 2cos x +1 = 0
rearrange
cos^2 x +2cos x + 1-sin^2 x = 0
1 - sin^2 x = cos^2 x trig identity
cos^2 x + 2 cos x + cos ^2 x = 0
combine like terms
2 cos ^2 x + 2 cos x = 0
divide by 2
cos ^2 x + cos x = 0
factor out a cos x
cos (x) (cos x +1) = 0
using the zero product property
cos (x) = 0 cos x + 1 =0
cos x =0 cos x = -1
taking the arccos of each side
arccos cos x = arccos (0) arccos (cos x) = arccos (-1)
x = pi/2, 3pi/2 x = pi
Jessica’s family arrived at 2:27-230
Answer:
||| First row: 11 -20 23 ||| Second row: -21 5 -24 ||| Third row: 6 9 -14 |||
Step-by-step explanation:
I wish I could explain it better, but all I did was plug it into matrix A on:
https://atozmath.com/matrix.aspx?q=minor
I pressed "find" without changing any of the settings, and scrolled down until I saw what was in the attached screenshot.
Each of the rows correspond to the first, second, and third answers, as you can see.
I hope this helps!
30% off
theh shirt is 22.40 after discount
original=100%
original-discount=22.40
100-30=70%
22.40=70%
percent means parts out of 100
22.40=70/100 of original
multiply both sides by 100/70 to clear fraction
2240/70=original
32=original
original=$32.00
