Absolute value of -1 +3i
1 answer:
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Answer:
x ∈ {2π/3, π, 4π/3} ≈ {2.09440, 3.14159, 4.18879}
Step-by-step explanation:
The equation can be put into standard form by adding 1:
2cos²(x) +3cos(x) +1 = 0
(2cos(x) +1)(cos(x) +1) = 0
Values of cos(x) that make this true* are ...
cos(x) = -1/2 . . . . . . . . . true for x=2π/3, x=4π/3
cos(x) = -1 . . . . . . . . . . . true for x=π
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A graphing calculator can be helpful here, too.
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* from your knowledge of the short table of trig functions and their signs in different quadrants
Answer:
(4,1)
Step-by-step explanation:
The vertex of the quadratic can be found using -b/2a. The vertex is the point (-b/2a, f(-b/2a)).
To find the x coordinate of the quadratic, define its a,b, and c. The quadratic has a = 2, b=-16, and c=31. Then -b/2a is -(-16)/2(2) = 16/4 = 4.
To find the y-coordinate, input the x=4 and solve for y.
The vertex is (4,1).