Q16 of 50 Page 28

A function is defined as follows


(i) 2f(-4) + 3f(2)


(ii) f (- 7) - f (- 3)


(iii)

We are given,


f: [-7,6)


[-7,6) = {x A: -7≤x<6}


= {-7, -6, -5, -4,-3, -2, -1, 0, 1, 2, 3, 4, 5}


And the function given are



(i) 2f(-4) + 3f(2)


Here the function lies between -5<x<2


So


f(x) = x + 5


f(-4) = -4 + 5


= 1


f(2) = 2 + 5


= 7


2f(-4) = 2 × 1 = 2


3f(2) = 3× 7 = 21


So 2f(-4) + 3f(2)


= 2 + 21 = 23


(ii) f (- 7) - f (- 3)


here the function lies between -7≤x<-5 and -5≤ x < 2


so f(x) = x2 + 2x + 1


f(-7) = (-7)2 + 2×(-7) + 1


= 49-14 + 1


= 36


Similarly f(x) = x + 5


f(-3) = -3 + 5


= 2


f (- 7) - f (- 3)


= 36 -2


= 34


(iii) .


For the above statement the function lies between


-7≤ x <-5 for f(-6)


-5≤ x<2 for for f(-3) and f(1)


2<x<6 for f(4)


at f(x) = x2 + 2x + 1 ; -7≤ x <-5


f(-6) = (-6)2 + 2(-6) + 1


= 36-12 + 1 = 25


At f(x) = x + 5; -5≤ x<2 for


f(-3) = -3 + 5 = 2


4f(-3) = 4 × 2 = 8


Similarly,


f(1) = 1 + 5 = 6


3f(1) = 3 × 6 = 18


At f(x) = x-1; 2<x<6


f(4) = 4-1 = 3


2f(4) = 2× 3 = 6


So the function given





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