The complete program is given below.
Translating the polynomial into Java is easy. Remember that x3 means x times itself three times. The statement that writes out the answer uses "+" to concatenate Strings. Remember that doubles are converted to String automatically when you use "+" with both a double and a String.
import java.io.*;
class evalPoly
{
public static void main (String[] args ) throws IOException
{
BufferedReader userin = new BufferedReader(new InputStreamReader(System.in) );
String xChars; // character version of x, from the user
double x; // a value to use with the polynomial
double result; // result of evaluating the polynomial at x
String response = "y"; // "y" or "n"
while ( response.equals( "y" ) )
{
// prompt the user and get a value for x
System.out.println("Enter a value for x:") ;
xChars = userin.readLine() ;
x = ( Double.valueOf( xChars ) ).doubleValue();
// evaluate the polynomial
result =7*x*x*x - 3*x*x + 4*x - 12;
// print out the result
System.out.println("The value of the polynomial at x = " +
x + " is :" + result + "\n" ) ;
// ask the user if program should continue
System.out.println("continue (y or n)?");
response = userin.readLine();
}
}
}
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