Tìm giá trị lớn nhất, nhỏ nhất: y= cos2x - 2sinx - 1 Giúp mình giải với ạ!!

Đáp án: Simplifying

cos2x + -2sinx + -1 = 0

Reorder the terms:

-1 + cos2x + -2insx = 0

Solving

-1 + cos2x + -2insx = 0

Solving for variable 'c'.

Move all terms containing c to the left, all other terms to the right.

Add '1' to each side of the equation.

-1 + cos2x + 1 + -2insx = 0 + 1

Reorder the terms:

-1 + 1 + cos2x + -2insx = 0 + 1

Combine like terms: -1 + 1 = 0

0 + cos2x + -2insx = 0 + 1

cos2x + -2insx = 0 + 1

Combine like terms: 0 + 1 = 1

cos2x + -2insx = 1

Add '2insx' to each side of the equation.

cos2x + -2insx + 2insx = 1 + 2insx

Combine like terms: -2insx + 2insx = 0

cos2x + 0 = 1 + 2insx

cos2x = 1 + 2insx

Divide each side by 'os2x'.

c = o-1s-2x-1 + 2ino-1s-1

Simplifying

c = o-1s-2x-1 + 2ino-1s-1

Reorder the terms:

c = 2ino-1s-1 + o-1s-2x-1

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