the linearization of f(x) = x^4 + 3x^2 with a = -1 is L(x) = 4 -
10(x+1)
the linearization formula is L(x) = f(a) + f'(a)*(x-a)
when, a = -1
f(a) = (-1)^4 + 3(-1)^2 = 4
f'(x) = 4*x^3 + 6*x
f'(a) = 4(-1)^3 + 6(-1) = -10
so, L(x) = (4) + (-10)*(x-(-1)) = 4 - 10(x+1)