## Intermediate Algebra (6th Edition)

$x=5$
A 2x2 determinant can be calculated as ad−bc, where a is the upper-left entry, b is the upper-right entry, c is the lower-left entry, and d is the lower-right entry. Therefore, the value of this determinant is $(1\times7)-(x\times2)=-3$ We can now solve this value for x. $7-2x=-3$ Subtract 7 both sides. $-2x=-10$ Divide both sides by -2. $x=5$