If a and b are zeroes of the x2 + 7 x+7, find the value of a−1+b−1−2ab.

9514 1404 393

  -15

Step-by-step explanation:

If 'a' and 'b' are zeros of the quadratic f(x), its factored form is ...

  f(x) = (x -a)(x -b)

and its standard form is ...

  f(x) = x^2 -(a+b)x +ab

This tells us that ...

  a+b = -7

  ab = 7

for the given quadratic.

Then the expression of interest is ...

solution:

as, mean is defined as sum of all the observations divided by total number of observations.

and , median is mid value of the data whether arranged in ascending order or descending order.

consider, roadsters:

2,3,4,5,6,7,8,9

mean =

also, median= , because number of observations is even, so median is mean of two mid values.

now, coming to bandits

2,3,4,5,6

mean =  

median = 4, as number of observations is odd.

so, roadsters has greater median as well mean than bandits.

→option a is true about the repairs performed on 2 types of cars:

bandits have lower median and mean than roadsters.

step-by-step explanation: