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If f(x) = 3x +9 x when f(x) = 30

Sagot :

Answer:

[tex]x=5/2[/tex]

Step-by-step explanation:

When [tex]f(x)=30[/tex], we have [tex]3x+9x=30[/tex].

Combining like terms on the right side, we have [tex]12x=30[/tex].

Finally, dividing by [tex]12[/tex] we get [tex]x=30/12[/tex].

We note that [tex]30=6*5[/tex] and [tex]12=6*2[/tex], so [tex]30/12=5/2[/tex].

So, [tex]\boxed{x=5/2}[/tex] and we're done!