If \( X^{-1}=\left[\begin{array}{ccc}1 & -2 & 0 \\ 0 & 1 & 1 \\ 0 & 0 & 2\end{array}\right] \), then the sum of elements in the \( 3^{r d} \) column of \( X \) is

The ratio between the sum of the fifth, sixth and seventh terms of a geometric series ind the sum of the first three terms of the same series is \( 81: 16 \). Determine the sum he first ten terms, if the first term is 1024 .

275. Використовуючи властивості віднімання, спрости вираз: \( \begin{array}{ll}\text { 1) }(37+a)-12 ; & \text { 2) }(b+415)-300 ; \\ \text { 3) } 42-(x+13) ; & \text { 4) } 517-(412+y)\end{array} \)

The sum of the first three terms of an arithmetic sequence is 15 and their product is 80. Determine the first threc terms.

Make \( d \) the subject of the relation in \[ W=M \sqrt{\frac{\left(D^{2}+d^{2}\right)}{2 d^{2}}} \]

Make d the subject of the relation in \[ W=\sqrt{\frac{\left(\Delta^{2}+d^{2}\right)}{2 d^{2}}} \]