Question

Необходимо решить задание по высшей математике

Answer 1

1. 
$3cdot left(begin{array}{ccc}2&1&3\1&3&4\2&1&1end{array}right) + left(begin{array}{ccc}1&-1&0\1&2&-1\-1&1&2end{array}right) cdot left(begin{array}{ccc}1&0&1\0&1&0\1&0&1end{array}right) =\\\= left(begin{array}{ccc}6&3&9\3&9&12\6&3&3end{array}right) + left(begin{array}{ccc}1&-1&1\0&2&0\1&1&1end{array}right)= left(begin{array}{ccc}7&2&10\3&11&12\7&4&4end{array}right)$

2.
$left|begin{array}{cc}1&2\4&7end{array}right|=1cdot 7 - 4cdot 2=-1.$

$left|begin{array}{cc}2&3\12&xend{array}right|=2cdot x - 12cdot 3=2cdot x - 36=0 , Rightarrow , x = 18.$

$left|begin{array}{cc}1&2\4&x-5end{array}right|=1cdot (x-5) - 4cdot 2 =x-5-8=x-13 textless 0, Rightarrow , x textless 13.$

3.
$left|begin{array}{ccc}1&2&3\2&3&1\1&3&2end{array}right|= 1cdot left|begin{array}{cc}3&1\3&2end{array}right| - 2cdot left|begin{array}{cc}2&1\1&2end{array}right| + 3cdot left|begin{array}{cc}2&3\1&3end{array}right| = 3 - 6 + 9 =6.$

$left|begin{array}{ccc}1&1&2\2&3&1\3&2&xend{array}right|= 1cdot left|begin{array}{cc}3&1\2&xend{array}right| - 1cdot left|begin{array}{cc}2&1\3&xend{array}right| + 2cdot left|begin{array}{cc}2&3\3&2end{array}right| = \\\ = 3x-2-(2x-3) -10=x-9=0 , Rightarrow,x = 9.$

$left|begin{array}{ccc}1&2&4\3&x&5\3&1&2end{array}right|= 1cdot left|begin{array}{cc}x&5\1&2end{array}right| - 2cdot left|begin{array}{cc}3&5\3&2end{array}right| + 4cdot left|begin{array}{cc}3&x\3&1end{array}right| = \\\ = 2x-5-2(6-15)+4(3-3x) = -10x+25 textless 0 Rightarrow x textgreater 2.5.$