Question

решите по теореме крамера  очень подробно.

Answer 1

$1); ; left { {{2x-4y=14} atop {4x+3y=-27}} right. \\Delta = left|begin{array}{cc}2&-4\4&3end{array}right| =6+16=22\\Delta _1= left|begin{array}{cc}14&-4\-27&3end{array}right| =42-108=-66\\Delta _2= left[begin{array}{cc}2&14\4&-27end{array}right| =-54-56=-110\\x=frac{-66}{22}=-3; ;; ; y=frac{-110}{22}=-5\\\2); ; left { {{3x+5y=14} atop {2x-4y=-20}} right. \\ Delta =left|begin{array}{cc}3&5\2&-4end{array}right| =-12-10=-22$

$Delta _1= left|begin{array}{cc}14&5\-20&-4end{array}right| =-56+100=44\\Delta _2= left|begin{array}{cc}3&14\2&-20end{array}right| =-60-28=-88\\x=frac{44}{-22}=-2; ;; ; y=frac{-88}{-22}=4$