Question

se f(x)=-7x+4, calcular os valores reais de x para que se tenha: f(x)=0 / f(x)=-12 / f(x)=4/9

Answer 1

 
 
 
 
f(x)=-7x+4,  f(x)=0 ==> -7x + 4 = 0 ==> -7x = -4(-1)
7x = 4 ==> x = 4/7
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 f(x)=-12 ==> -7x + 4 = 12 ==> -7x = -12-4(-1)==> 7x = 16==> x = 16/7

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f(x)=4/9 ==> -7x + 4 = 4/9 ==> -7x = -4+4/9(-1)63x = - 63 +4 ==> x = - 59/7