19. Let A be a lower triangular n n matrix with nonzero entries on the diagonal. Show that A is invertible and A1 is lower triangular. [Hint: Explain why A can be changed into I using only row replacements and scaling. (Where are the pivots?) Also, explain why the row operations that reduce A to I change I into a lower triangular matrix.]

The two expressions below have the same value when rounded to the nearest hundredth. log5 b log9 48 what is the approximate value of log b to the nearest hundredth? 0.93 1.23 9.16 65.53

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

If you could answer these your a life saver