A *( 1-x)*( 1-x)= A *( 1-0. 19)
Lower the price twice on the left and once on the right 19%.
The x of the solution is x=0.09, that is, 9%.
(2) Set the original price of air conditioner as B, according to the meaning of the question.
Scheme No.1
The final price of each air conditioner is B*( 1-0.05)+90.
Option 2
The final price of each air conditioner is B*( 1-0.02).
Compare the two schemes.
When the first scheme is superior to the second scheme, there are
b *( 1-0.05)+90 < b *( 1-0.02)
b \u 3000
Similarly, when the second scheme is superior to the first scheme, there are
B *( 1-0.05)+90 > B *( 1-0.02)
3000 pounds
Therefore, when the price of air conditioner is more than 3000 yuan, the first scheme should be chosen; When the price of air conditioner is less than 300, scheme 2 should be selected; When the price of air conditioner is 3000 yuan, the two schemes are the same.