1. If A/ C Rix2 is positive semidefinite, then M/ is invertible. 2. The maximum rate of change of a differentiable function ,: R) -> R at r E R3 is given by ( Vg(a)|. 3. If #1 : R -+ R is a solution to the differential equation ?"(r) + 27'(x) + 4y(r) =0, then y, : R - R with $2(r) = 2y1 (x) is a solution to the same equation. 4. If f. R' - R is differentiable and.v = (-1,0). then # (ry) - - 5. If M is a negative-definite 2 x 2-matrix, then det (1/)