Cos^2(x) - sin^2(x) = 1
cos(2x) = 1
2x = π/2 + 2πk
x = π/4 + πk
A)<u>
5а</u> + 7b - <u>2а</u> - 8b = a(5 - 2) + b(7 - 8).
Б)
3(4х + 2) - 5 = 12x + <u>6</u> - <u>5</u> = 12x + 1.
B)
<span>20b - (b - 3) + (3b - 10)</span> = <u>20b</u> - <u>b</u> + 3 + <u>3b</u> - 10 = 22b - 7.
5x+48:4= 20:10+2*10
5х+48:4= 22
5х+12=22
5х=22-12
5х=10
Х=10:5
Х=2