Question

Срочно!!! Завдання на фото

Answer 1

$\displaystyle\bf\\Cos\Big(2x-\frac{\pi }{4}\Big)=1 \\\\\\2x-\frac{\pi }{4}=2\pi n,n\in Z\\\\\\2x=\frac{\pi }{4} +2\pi n,n\in Z\\\\\\x=\frac{\pi }{8} +\pi n,n\in Z\\\\\\-\frac{\pi }{2} < \frac{\pi }{8} +\pi n < \frac{\pi }{2} \ |\cdot 8\\\\\\-4\pi < \pi +8\pi n < 4\pi \ |:\pi \\\\\\-4 < 1+8n < 4\\\\\\-5 < 8n < 3\\\\-0,625 < n < 0,375$

Ответ : одно решение при n = 0