Does this
f(x)=x3−12x2+28x−9
change to
f(−x)=−x3+12x2−28x−9 ?

Question

Does this
f(x)=x3−12x2+28x−9
change to 
f(−x)=−x3+12x2−28x−9     ?

anonymous · Answer

or am i doing it wrong?

anonymous · Answer

And this one...

this
f(x)=x4−x3+7x2−9x−18
to this
f(−x)=x4+x3+7x2+9x−18

anonymous · Answer

2nd one is absolutely right.

anonymous · Answer

thats what i put didnt i?

anonymous · Answer

odd powers doesnt affect negative sign
but even power do change.

anonymous · Answer

i wrote wrong expression.sorry my fault.but I hope u understood the method.

anonymous · Answer

what? isnt it odd exponents cause the x to be replaced with -x? and even exponents stay the same?

anonymous · Answer

@heybhai

jdoe0001 · Answer

hmm, if the exponent is odd, the -x will change the term, if it's even, it won't

anonymous · Answer

okay well he told me differently but he still gave me the same function i wrote and said i was wrong. im confused

anonymous · Answer

is the first one converted right?

anonymous · Answer

(-x)^3-12(-x)^2+28(-x)-9
-x^3-12x-28x-9

This is right one

jdoe0001 · Answer

$\bf f(x)=x^3−12x^2+28x-9\
\text{change to }\
f(-x)=(-x)^3−12(-x)^2+28(-x)-9\\ \implies f(x)=-x^3−12x^2-28x-9$

anonymous · Answer

but 12x^2 has an even exponent....

jdoe0001 · Answer

12x^2 is negative from the beginning
so it keeps whatever sign it had before

jdoe0001 · Answer

if the exponent is even, the -x doesn't change the sign

anonymous · Answer

oh okay i think i just over looked that. thanks for clearing it up(:

jdoe0001 · Answer

$\bf -12(-x)^2 \implies -12(-x)(-x) \implies -12(+x)^2$