Use CAS: Make a function f(x)=x²-6x+5.
Use CAS: Find the point, where x1=2
Use CAS: Find f '(x) and the slope a = f '(x1)
Use CAS and formula: Find the tangent line.
Use tangent in the input field to check your result. 

Make a slider for x1.
Use CAS: Make a function f(x)=x²-6x+5.
Use CAS: Find the point with x1.
Use CAS: Find f '(x) and and the slope a = f '(x1)
Use CAS and formula: Find the tangent line.

x-value

y-value

Day

Meter

A2 = 3
B2 = 4.5
A3 = 6
B3 = 7.2
A4 = 8
B4 = 9.9
A5 = 11
B5 = 12.9
A6 = 14
B6 = 14.9
E2 = 1
E3 = 2
E4 = 3
E5 = 4
E6 = 5
E7 = 6
E8 = 7
F2 = 841.2
F3 = 848.3
F4 = 857.9
F5 = 866.5
F6 = 874.2
F7 = 885.6
F8 = 895.9
x1 = 1.2 (slider from -5 to 5, step 0.1)
f(x) = x^(3) - (4 * x^(2)) + (3 * x)
y1 = -0.432
a = -2.28
A = (1.2, -0.432)