4. Let \( f(x)=k-x^{2} \). Find the value of \( k \) such that the line \( y=-6 x+1 \) is tangent to the of \( f(x) \).

Add \( 5 \mathrm{a}-3 \mathrm{~b} \) and \( -5 \mathrm{~b}+3 \mathrm{a} \) the result is ...... \[ \begin{array}{l}8 \mathrm{a}-8 \mathrm{~b} \\ 8 \mathrm{a}+8 \mathrm{~b} \\ 8 \mathrm{~b}-8 \mathrm{a} \\ 2 \mathrm{a}-2 \mathrm{~b}\end{array} \]

\( 3 x-2 y=7 \) (1) \( y+2 y=14 \) (2)

which of the following equations is not a linear function? 1) \( 2 y-3 x=1 \) 2) \( 4 x^{2}+y^{2}=4 x y \) 3) \( y=2 \) 4) \( x=2 \)

\( \equiv \) (i) Listen A bowl contains blueberries and strawberries. There are a total of 12 berries in the bowl. The ratio of blueberries to strawberries is 1 to 2 . How many of each berry are in the bowl? \( \square \) blueberries strawberries

4. Make \( c \) the subject of \( g=\frac{c+3}{4+c}-7 \)