A. that is b^2-4ac for ax^2+bx+c the deterimant (part under the radicand) is b^2-4ac if it is 1. less than 0 then there are no real solutions 2. eqal to 0 then there is 1 real solution 3. greater than 0, there are 2 real roots 9x^2-16x+60 b^2-4ac=(-16)^2-4*9*60=256-2160<0 no real solutions
B. grouping ac method 4 times -5=-20 what 2 numbers multiply to get -20 and add to get 8? -2 and 10 seperate the middle number to get that 4x^2-2x+10x-5=0 (4x^2-2x)+(10x-5)=0 2x(2x-1)+2(2x-1)=0 (2x-1)(2x+2)=0 set equal to 0
to figure out the percent decrease, subtract the percent from 100. then divide by 100 to get a decimal. multiply that decimal by the original cost to get the answer.
