[main] Finished module 2.1

Author: cthacker-udel

pythonProblems/matrixpractice/quiz1.md

@@ -0,0 +1,26 @@
+He wants to invest his USD $10,000 savings in these three accounts
+
+he knows that **after a year he would receive a total of US $ 260 in interest** if he put **twice as much money in the savings account as in the CDs**, and **“z” money in bonds**.
+
+x = money in cds
+z = money in bonds
+
+2x + x + z = 260
+
+3x + z = 260
+z = 260 - 3x
+
+a + b + z = 10000
+2a + b + z = 260
+
+a + b/2 + z/2 = 130
+
+- -a -b -z = -10000
+
+---
+
+       -b/2 -z/2 = -9870
+
+-b/2 - z/2 = -9870
+
+-.5b - .5z = -9870

pythonProblems/matrixpractice/rowreduction.py

@@ -0,0 +1,103 @@
+mat1 = [[5, 1], [4, -3]]
+mat2 = [[1, 0.2], [0, 1]]
+
+# x + y = 4
+# -6x + 2y = 16
+
+
+# x -2y/6 = 16
+
+
+# x - y/3 = 16/-6
+
+# x - y/3 = -2.6
+
+# x -1/3y = -26
+
+#     x - y = -26/3
+# -   x - y = -4
+# ---------------------
+
+
+#       -2y = -12/3 + 26/3
+#       -2y = -38/3
+#         y = 6.3
+
+# x + 6.3 = 4
+# x = -2.3
+
+
+mat1 = [[4, -3], [7, -8]]
+
+dt_1 = mat1[0][0] * mat1[1][1]
+dt_2 = mat1[0][1] * mat1[1][0]
+
+dt_one = dt_1 - dt_2
+
+print(dt_one)
+
+
+mat1 = [[-3, -8, 1], [2, 2, -1], [-5, 6, 2]]
+
+dt_1_1 = mat1[0][0] * mat1[1][1] * mat1[2][2]
+dt_1_2 = mat1[0][1] * mat1[1][2] * mat1[2][0]
+dt_1_3 = mat1[0][2] * mat1[1][0] * mat1[2][1]
+
+dt_anti_1 = mat1[0][2] * mat1[1][1] * mat1[2][0]
+dt_anti_2 = mat1[0][1] * mat1[1][0] * mat1[2][2]
+dt_anti_3 = mat1[0][0] * mat1[1][2] * mat1[2][1]
+
+dt_1_full = dt_1_1 * dt_1_2 * dt_1_3
+dt_1_anti_full = dt_anti_1 * dt_anti_2 * dt_anti_3
+
+print(dt_1_full - dt_1_anti_full)
+
+# [[1, 1], [2, 3]]
+
+# a + 2b + z = 260
+
+
+# a/2 + b + z/2 = 130
+
+
+# x + y = 4
+# -6x + 2y = 16
+
+# x + y = 4
+# x + -1/3y = 16/-6
+
+# x + -1/3y = -2.6
+# - x + y = 4
+
+
+# -4/3y = -6.6
+# y = 5.0
+
+# x + 5 = 4
+# x = -1
+
+
+# x + 2x + z = 3x + z = 10000
+
+# z = 10000 - 3x
+
+# 0.02(2x) + 0.03(x) + 0.04(z) = 0.04x + 0.03x + 0.04z = 0.07x + 0.04z
+
+# # total interest earned is 260
+
+# 0.07x + 0.04z = 260
+
+# 3x + z = 10000
+# 0.07x + 0.04z = 260
+
+
+# multiply second by 3
+# 0.21x + 0.12z = 780
+
+# subtract second from first
+
+
+#   3x + z = 10000
+# - 0.21x - 0.12z = -780
+
+# 2.79x + 0.12z