Question

Determine X e Y a fim de que: $\left[\begin{array}{ccc}2&x&\\y&-3&\\\end{array}\right] . \left[\begin{array}{ccc}4\\-5\\\end{array}\right] = \left[\begin{array}{ccc}-2\\-1\\\end{array}\right]$

Answer 1

(2 * 4) + (x * (-5)) = -2
(y * 4) + (-3 * (-5)) = -1
8 + (-5x) = -2
4y + 15 = -1

8 -5x = -2
-5x = -2 - 8
-5x = -10
x = 10/5
x = 2

4y +15 = -1
y = -16/4
y = -4