20. ( 4 points) A weight hooked onto the end of a spring fixed to a ceiling bounces up and down. The weight's height, \( h \), relative to the ground, in metres, is given by the formula \( h=0.25 \sin (240 t-90)+1.5 \), where \( t \) is the time, in seconds. a) What is the weight's initial height? b) How high off the ground is the weight when it is midway between its highest and lowest points? c) What is the weight's maximum height? d) d) What is the height after \( 2.5 s \) ?

\( x ^ { 3 } \sin ( x ) \cdot \sin | x | + \cos ( x ) \cdot ( x ^ { 3 } \cdot \cos ( x ) + \sin ( x ) \cdot 3 x ^ { 2 } ) \)

Find the solutions of the quadratic equation \( x^{2}+x+1=0 \) Choose 1 answer: (A) \( \frac{1}{2} \pm \frac{\sqrt{3}}{2} i \) (B) \( -\frac{1}{2} \pm \frac{\sqrt{3}}{2} \) (C) \( -\frac{1}{2} \pm \frac{\sqrt{3}}{2} i \) (D) \( \frac{1}{2} \pm \frac{\sqrt{3}}{2} \)

\( \vec { a } = ( 4 + | \vec { a } | , - 2 - | \vec { a } | ) \)

3 A sum of money was invested 6 years ago, earning interest at a rate of \( 6,7 \% \) p.a. compounded annually. The investment is currently worth \( \mathrm{R} 96714,02 \). Calculate how much was originally invested 6 years ago.

ion 4 \( \sin \left(\frac{7 \pi}{2}\right)=\square_{\text {exact value }}^{\square} \) Question