4) Solve the system of equations. \( \begin{array}{l}y=21 x+31 \\ y=3 x^{2}+21 x-17\end{array} \)

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

8. \( \frac{\sqrt{27 a^{3} b^{6}}}{\sqrt{3 a b^{6}}-5 a b^{2}}= \)

Subtract the polynomials: \( (5x^{3} + 2x^{2} - 7) - (3x^{3} - x^{2} + 4) \)

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