Question

Dada a função f(x) =ax+b,sabendo que f(1)= 5 e f(-3)= -7
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Answer 1

$f(x) = ax + b\\\\1) \\f(1) = a + b\\ 5 = a +b \\\\2)\\f(-3) = ax + b\\-7 = -3a + b\\\\ \left \{ {{-3a +b = -7} \atop {a + b =5}} \right. (-) \\\\\\-4a = -12\\a = 12/4\\a = 3 \\\\\\ a +b = 5 \\b = 5-3\\b = 2\\\\ f(x) = 3x + 2$

Answer 2

Olá!!!

Resoluçao!!!!

f ( x ) = ax + b

• f ( 1 ) = 5 → a • ( 1 ) + b = 5 → a + b = 5

• f ( - 3 ) = - 7 → a • ( - 3 ) + b = - 7 → - 3a + b = - 7

Sistema :

{ a + b = 5
{ - 3a + b = - 7

a + b = 5
a = 5 - b

- 3a + b = - 7
- 3 • ( 5 - b ) + b = - 7
- 15 + 3b + b = - 7
3b + b = - 7 + 15
4b = 8
b = 8/4
b = 2

a = 5 - b
a = 5 - ( 2 )
a = 5 - 2
a = 3

a = 3, b = 2

f ( x ) = ax + b → f ( x ) = 3x + 2

Espero ter ajudado!!!