A) There are a number of ways to compute the determinant of a 3x3 matrix. Since k is on the bottom row, it is convenient to compute the cofactors of the numbers on the bottom row. Then the determinant is ...
1×(2×-1 -3×1) -k×(3×-1 -2×1) +2×(3×3 -2×2) = 5 -5k
bi) Π₁ can be written using r = (x, y, z).
Π₁ ⇒ 3x +2y +z = 4
bii) The cross product of the coefficients of λ and μ will give the normal to the plane. The dot-product of that with the constant vector will give the desired constant.
Π₂ ⇒ ((1, 0, 2)×(1, -1, -1))•(x, y, z) = ((1, 0, 2)×(1, -1, -1))•(1, 2, 3)
Π₂ ⇒ 2x +3y -z = 5
c) If the three planes form a sheath, the ranks of their coefficient matrix and that of the augmented matrix must be 2. That is, the determinant must be zero. The value of k that makes the determinant zero is found in part (a) to be -1.
A common approach to determining the rank of a matrix is to reduce it to row echelon form. Then the number of independent rows becomes obvious. (It is the number of non-zero rows.) This form for k=-1 is shown in the picture.
Step-by-step explanation:
The reserve ratio is the central bank's mandate for banks to keep a certain reserve requirements, which are excess cash deposits that must be kept on hand and not loaned out.
Raising the ratio is contractionary since less loans can be made, but this also solidifies banks' balance sheets.
If the Federal Reserve instead lowers the reserve ratio through an expansionary monetary policy, commercial banks are required to hold less cash on hand and can make more loans.
Answer:
y = -28 ÷ x
Step-by-step explanation:
The standard format of a inversely proportional equation goes by the format of y = k ÷ x. The question asks us to write an equation if y = 7 when x = -4 and y varies inversely with x.
So we substitute the values y = 7 and x = -4 in the equation y = k ÷ x
K = constant, we have to work this out
7 = k ÷ -4
7 × - 4 = k
k = - 4 × 7
k = -28
k = -28 So then we put this back into the original y = k ÷ x to find our final equation which is y = -28 ÷ x