7. Austin solved the equation as shown below. Which correctly describes the error that Austin made in his work? \[ \begin{array}{cl}\text { Austin's work: } & \text { A. Austin did not combine } 7 x \text { and } 8 x \text { correctly. } \\ -3+7 x-9+8 x=54 & \text { B. Austin did not combine }-3 \text { and }-9 \text { correctly. } \\ 15 x-6=54 & \text { C. Austin did not divide correctly. } \\ 15 x=60 & \text { D. Austin did not make an error in his work. } \\ x=4 & \end{array} \]

Câu 03: (a) Rût gơn biểu thực \[ \left(\frac{1-x}{x^{2}+x^{3}-x^{4}}-\frac{x^{2}+x+2}{x^{5}-x^{3}-2 x^{2}-x}\right):\left(\frac{1+x^{4}}{x^{3}+x^{4}+x^{5}}-\frac{1-x+x^{2}}{x}\right) \] (b) Phân tích phân thức \( \frac{1}{(x-1)(x-2)(x-3)(x-4)} \) thành tổng các phân thức dơn giản.

Câu 01: (a) Cho hàm số \( f(x)=a x^{2}-\sqrt{2} \). Tìm \( a \) biết rằng \( (f \circ f)(\sqrt{2})=-\sqrt{2} \). (b) Tìm \( m \) để hàm số \( y=\sqrt{2 x-3 m+4}-\frac{x-m}{x+m-1} \) xác định với mọi \( x>0 \).

QUESTION 12 If \( 2^{x} 5^{y}=16 \times 125 \), where \( x \) and \( y \) are positive integers, determine \( x-y \) :

\( f(x)=5 x+6 ; g(x)=3 x-2 \) (h) Find \( \left(\left.\bar{g}\right|^{(1)}\right. \) \( \left(\frac{f}{g}\right)(1)=\square \) (Type an integer or a simplified fraction.)

\( x^{2}-(k+3) x-7=0 \) seja igual a 8