y=f(a)+f'(a)(x-a)
f(a) = 1/4(2-1)^2 = 1/4 = 0.25

f'(x) = 1/4 * (1/(2x-1)^2)'= 1/4 * ((2x-1)^-2)'= 1/4 * (-2(2x-1)^-3) * 2=1/2 * (-2/(2x-1)^3) = -1/(2x-1)^3
f'(a) = -1/(2-1)^3 = -1

y=0.25 -(x-1) = 0.25 - x + 1= -x+1.25

y= -x+1.25