f(x)= 4x^2+5x-7 . persamaan garis normal kurva yang melalui x=2

f(x) = 4x² + 5x - 7
f'(x) = m = 8x + 5
substitusikan x = 2 pd m dan f(x)
m = 8(2) + 5 = 21
tgk lurus → m1 = -1/m = -1/21
y = 4(2)² + 5(2) - 7 = 19
titik (2, 19)
y - y1 = m1(x - x1)
y - 19 = -(1/21)(x - 2)
21y - 399 = -x + 2
21y + x - 401 = 0