Question 1121228
In the expression (ax + by)(cx - dy), a, b, c, and d are non-zero constants and ad = bc. If ac = 18 and bd = 50, what is the value of the coefficient of the xy term when the expression is multiplied out and the like terms are collected?
<pre>After FOILING, you should get: {{{(ac)x^2 - (ad - bc)xy - (bd)y^2}}}, and since ad = bc, then ad - bc = ad - ad, or bc - bc = 0, and so, we get: 0xy.
Therefore, coefficient on the xy term is 0. All other answers are WRONG, so IGNORE them.