A certain type of chocolate bar is sold as follows. Single chocolate bar: 82p, or buy one get one half price

Packs of 5: £3, offer: 2 packs for £5.75

Packs of 10: £6 each

What's the cheapest way of buying exactly 38 chocolate bars without any extra?

Find the amount of each type of pack or single bar you need and the total cost of buying 38 packs.

Step-by-step explanation:

You would never buy a 10-pack, because two 5-packs cost less.

To buy 3 bars you need a single bar and a pair of single bars for £0.82 + £0.82+ £0.41 = £2.05

To buy 30 bars you need 3 pairs of 5-bar packs = 3×£5.75 =  £17.25

To buy the remaining 5 bars you need one 5-bar pack = £3

cost = £2.05 + £17.25 + £3 = £22.30

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.