FUNCTIONS D3

Given that F(x) = 3x  +  11. Find F(-2) – 2F(5)

 

Solution

 

CASE 1: We find F(-2)

 

 

F(x) = 3x  +  11

 

F(-2) = 3(-2)  +  11

 

F(-2) = -6  +  11

 

F(-2) = 5

 

 

Hence  F(-2) = 5

 

 

 

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CASE 2: We find F(5)

 

 

 

F(x) = 3x  +  11

 

F(5) = 3(5)  +  11

 

F(5) = 15  +  11

 

F(5) = 26

 

 

Hence  F(5) = 26

 

 

2F(5) = 2(26) = 52

 

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CASE 3: We find F(-2) – 2F(5)

 

 

= F(-2) – 2F(5)

= 5 – 52

= -47

 

 

TRY THIS………………..

 

 

 

Given that F(x) = 12x  +  78. Find F(-20) – 2F(10)