Question

find all solutions of 2 cos^2 x+ cos x-1=0. Hint: find all the solutions on[0,2pi]; then use periodicity to express all the solutions by adding arbitrary integer multiples of the appropriate angle(s). Express answers to three decimal places

Answer 1

3) Graph this equation. Since we want all answers, set the plotting range for x → [-7, 7] and y → [-3, 3]’ Find the period by looking at the graph. Solve the equation 2y2 + y – 1 = 0, using the equation solver. The y you find is the cos x. The question is what angle has a cos equal to y? Look on the unit circle.

Answer 2

I solved for y and got -1 and 1/2