Senior 1 Algebra \( \begin{array}{lll}\text { If } f(x)=3 x, \text { then the sign of the function is negative in the interval }] \\ \text { (a) }]-\infty[ & \text { (b) }] 3, \infty[ & \text { (c) }]-\infty, 0[ \\ \text { Sol }]-3, \infty[ \end{array} \) Solution

\( \left. \begin{array} { l } { ( x + y ) ^ { 3 } = z } \\ { ( y + z ) ^ { 3 } = x } \\ { ( z + x ) ^ { 3 } = y } \end{array} \right. \)

Three quantities \( t, x \) and \( y \) are such that \( t \) varies directly as \( x \) and invisely as the square root of \( y \). Find the percentage decrease in \( t \) if \( x \) decreases by \( 44 \% \).

Cho hàm số \( f x=\left\{\begin{array}{ll}\frac{\sqrt{4 x+1-1}}{a x^{2}+(2 a+1) x 0} & \text { khi } x \neq 0 \\ 3 & k h i \quad x=0\end{array}\right. \). Biết rằng \( a \) là giá trị đề hàm số liên tu \( =0 \), hãy tìm số nghiệm nguyên của bất phương trình \( x^{2}-x+36 a<0 \).

212 / बीजगणित (Algebra) 24. यदि \( 4,2 x-4, \ldots \ldots, 64,21 x+2 \) एउटा गुणोत्तर अनुक्रमको पदहरू भए, If \( 4,2 x-4, \ldots \ldots, 64,21 x+2 \) are the terms of geometric sequence (i) \( x \) को मान पत्ता लगाउनुहोस् । (Find the value of \( x \).) (ii) समान अनुपात पत्ता लगाउनुहोस् । (Find the common ratio.) (iii) चौथो पद पत्ता लगाउनुहोस् । (Find the value of fourth term.)

\( \left. \begin{array} { l } { x ^ { 2 } - y ^ { 2 } + y } \\ { = 3 x ^ { 2 } y - y ^ { 3 } + x y } \end{array} \right. \)