Consider the function f(x)=7x2+3 Its tangent line at x=4 goes through the points (5,y1) and (−6,y2). What is y1 and y2?

Answer 1

f(4) = 115; f'(x) = 14x; f'(4) = 56; equation of tangent line y = 115 + 56(x - 4) or y = 56x - 109;

if x = 5 y₁ = 171;

if x = - 6 then y₂ = 56·(-6) - 109 = - 445.