f(x) is a function such that f(x) = s(x)+p(x), where s(x) is the sum o

Question

f(x)  is a function such that  f(x) = s(x)+p(x) , where  s(x)  is the sum of all the digits of  x  and  p(x)  is the product of all the digits of  x.

Identify one x-value that, entered into function f(x), would yield an appropriate result. Select only one answer in each column.

doe007 · Answer

What is the source of the question? 
Wordings of the question does not convey the question properly. It is not clear that "appropriate result" is appropriate to what. Is the question asking for the case where x = f(x), or is the question asking to find one value of x from "Options for x-value" for which there is a corresponding f(x) in "Options for result".

arpanpatnaik · Answer

I guess if we assume, Column 1 represents all the values for var x, and Column 2 represents the values of f(x), the values 39 and 39 satisfy for obvious reasons.
f(39) = s(39) + p(39)
=> 12 + 27 = 39.

But as previously mentioned, the question does offer some ambiguity.

Regards,
Arpan

skriaras@hotmail.com · Answer

Hi everyone ! This problem can be effectively solved through algebraic approach. More specifically..

Since 5 out of 6 answer choices are two digit numbers, lets  assume  that  "x"  is a two digit  number    "ab"  ,  a  : tens digit and  b  : units digit

So  ab  equals  10*a+b

Finally If you solve the following equation : 10*a+b = a+b + a*b ...... you will come up with the solution b=9 ,

thus we have no other choice except for --> 39 for "x" value, (since it is the only two digit number that ends in 9) and

solve the equation to find the y value.

This simple approach, by solving an extremely easy equation, saves time from trial and error, where you might end up trying to input 5 numbers to x and solve the equation the equation to find y..

ruis · Answer

Hi there! Why do you multiply by 10?
Wouldnt ab (aka "x") = (a+b) +(a*b)?

bumpbot · Answer

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x-value	Result	-----------
		24
		39
		48
		68
		256

f(x) is a function such that f(x) = s(x)+p(x), where s(x) is the sum o

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f(x) is a function such that f(x) = s(x)+p(x), where s(x) is the sum o

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