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2nd Year Functions Help
by joecole Junior Cert Mathematics — 26/05/16 8

Can anyone help me with this question please? The function "f" is defined by f:x = 7-3x. If f(24) = kf (-2), find the value of k. Thanks.


8 Comments
Cutclutc — 22/05/16
i think that the answer is k = 5 f:x = 7-3x f(24) = 7-3(24) f(24) = 7-72 f(24) = -65 kf(-2) = k(7-3(-2)) f(-2) = 13 k = 65/13 k = 5
joecole — 22/05/16
Thanks a million. That the answer in the marking scheme.
AssemblyRequired — 23/05/16
Just a question: if f(24)=-65, how come at the end k=65/13 (note the difference in sign).
AssemblyRequired — 23/05/16
Here's how I worked it out: f(24)=7-72 =-65 kf(-2)=k(13) =13k -65=13k -65/13=13k/13 -5=k
mossy_oc — 26/05/16
If you have a Casio calculator you can press mode 3 then put in the function and the range and it gives you the answer in a table
mossy_oc — 26/05/16
If you're drawing a graph
mossy_oc — 26/05/16
Of a function
joecole — 26/05/16
Thanks, but it was just to solve for 'k'.
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