Let fƒ: R2 → R be defined by f(x) = -12r2 + 4x² + 4x² - 4x122. Write f as with a positive definite symmetric matrix A € M₂ and b E R2. To d₁ := (1,0) find all the vectors d₂ R2 such that the pair (d₁, d2)T is A-conjugate.