Suppose matrices \( M \) and \( N \) are the same size, so their sum is defined. Is the following trye or false? \( \begin{array}{l}M+N=N+M \\ \text { True. } \\ \text { False. }\end{array} \).

Diketahui sistem persamaan tinier berikut ini : \[ \begin{array}{l}-1 x+y+2 z=2 \\ 3 x-1 y+z=6 \\ -1 x+3 y+4 z=4\end{array} \] Tentukan solusi persamaan linear tersebut menggunakan metode gauss!

tinh \( a x^{2}+2 x+3 y=6 \)

Roger was told to think of a number, add 20 , then divide the result by 3 . The answer was Jower than Roger's original number. Deteruine the range of possible numbers Roger may have originally chosen.

(b) \( \frac{3}{x-1}<\frac{2}{x} \)

In the \( x y \)-plane, a parabola has vertex \( (9,-14) \) and intersects the \( x \)-axis at two points. If the equation of the parabola is written in the form \( y=a x^{2}+b x+c \) where \( a, b \), and \( c \) are constants, which of the following could be the value of \( a+b+c \) ? (A) -23 (B) -19 (D) -12