Question 111269

{{{f(x)=x^3+3x^2-5x+8}}} Start with the given function.



{{{f(4)=(4)^3+3(4)^2-5(4)+8}}} Plug in {{{x=4}}}. In other words, replace each x with 4.



{{{f(4)=(64)+3(4)^2-5(4)+8}}} Evaluate {{{(4)^3}}} to get 64.



{{{f(4)=(64)+3(16)-5(4)+8}}} Evaluate {{{(4)^2}}} to get 16.



{{{f(4)=(64)+48-5(4)+8}}} Multiply 3 and 16 to get  48



{{{f(4)=(64)+48-20+8}}} Multiply -5 and 4 to get  -20



{{{f(4)=100}}} Now combine like terms


Since {{{f(4)<>0}}}, this means that {{{x=4}}} is not a zero