4 cos² x - 3 = 0
4 cos² x = 3
cos² x = 3/4
cos x = ±(√3)/2
Fixing the squared cosine doesn't discriminate among quadrants. There's one in every quadrant
cos x = ± cos(π/6)
Let's do plus first. In general, cos x = cos a has solutions x = ±a + 2πk integer k
cos x = cos(π/6)
x = ±π/6 + 2πk
Minus next.
cos x = -cos(π/6)
cos x = cos(π - π/6)
cos x = cos(5π/6)
x = ±5π/6 + 2πk
We'll write all our solutions as
x = { -5π/6, -π/6, π/6, 5π/6 } + 2πk integer k
Answer:
The second graph.
Step-by-step explanation:
The first graph has a negative slope, so that can't be the right answer.
The last graph isn't steep enough to show a rate of 2.5.
This leaves us with the middle graph which is correct.
Answer:
x = 3
y = -1
Step-by-step explanation:
(x-y) + (x+y) = 4 + 2
2x = 6
x = 3
sub x=3 into x+y=2
3+y=2
y=2-3
y=-1
Check by subbing x=3 and y=-1 into x-y=4
(3)-(-1) = 3+1 = 4
41, because the ratio is the same
