If f(x) varies directly with x and f(x) = 24 when x = –4, then what is f(x) when x = 12?

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Answer 1 · 2018-07-19T11:10:02

#f(12)=-72#

Given that #f(x)# varies directly with #x# hence let

#f(x)=kx#

Where #k# is some arbitrary constant

Now, given that #f(-4)=24# hence

#k(-4)=24#

#k=-6#

#\implies f(x)=-6x#

#\therefore f(12)=-6(12)#

#=-72#