Question

Dada a função f (x)  = 2 x+ 5, calcule x para que:
a) f (x) = 5
b) f (x)  = 1
c) f (x)  = -1

Answer 1

f (x)  = 2 x+ 5

a) f (x) = 5 ==> 2x+ 5 = 5==> 2x = 5-5==> 2x = 0 ==> x = 0
b) f (x)  = 1==> 2x+ 5 = 1==> 2x = 1-5==> 2x = -4 ==> x = - 2
c) f (x)  = -1 ==> 2x+ 5 = -1==> 2x = -1-5==> 2x =-6 ==> x = - 3

Answer 2

f(x) = 2x + 5 ,  x = ? para:
a)  2x + 5 = 5    2x = 0      x  =  0
b)  2x + 5 = 1    2x = - 4    x = - 2
c)  2x + 5 = -1   2x = - 6    x = - 3