Find the value of the expression: 1) 6sin ^ 2 * x-4 if cos ^ 2 * x = 3/42) 4-2cos ^ 2 * x if sin ^ 2 * x = 0.75

Let’s use trigonometric equality:
cos ^ 2 (α) + sin ^ 2 (α) = 1;
1) If cos ^ 2 (x) = 3/4,
then sin ^ 2 (x) = 1 – cos ^ 2 (x) = 1 – 3/4 = 1/4;
Substitute this value into the expression
6 * sin ^ 2 (x) – 4 = 6 * 1/4 – 4 = -2.5.
2) If sin ^ 2 (x) = 0.75,
then cos ^ 2 (x) = 1 – sin ^ 2 (x) = 0.25;
Substitute this value into the expression
4 – 2 * cos ^ 2 (x) = 4 – 2 * 0.25 = 4 – 0.5 = 3.5.