posted by mysterychicken .
Need help with these--
40. The graph of the following system yields perpendicular lines:
x + 2y = -10
-4y = 2x + 20
True or False?
42. If we multiply a 2 x 2 matrix with a 2 x 1 matrix, the product is a 2 x 1 matrix.
41. False. If you solve both equations for "y", you will get the same line; which means they can not be perpendicular.
42. True. When you have two matrices multiplied together, (2 x 2)(2 x1). If the two inner numbers match, then your resulting matrix will be the two outer numbers.