What is 26?

"26. Basics 26.6.2. Computing Quadratic Roots Some programs require the user to enter multiple inputs. The prompt-input process can be repeated. In this example, consider asking the user for the coefficients, a, b, c to a quadratic polynomial, ax 2 + bx + c and computing its roots using the quadratic formula, x = − b ± √ b 2 − 4 ac 2 a As before, we can create a basic program with a main() method and start filling in the details. In particular, we’ll need to prompt for the input a , then read it in; then prompt for b , read it in and repeat for c . We’ll also need several variables: three for the coefficients a, b, c and two more; one for each root. 1 double a, b, c, root1, root2; 2 Scanner s = new Scanner(System.in); 3 4 System.out.println(\"Please enter a: \"); 5 a = s.nextDouble(); 6 System.out.println(\"Please enter b: \"); 7 b = s.nextDouble(); 8 System.out.println(\"Please enter c: \"); 9 c = s.nextDouble(); Now to compute the roots: we need to adapt the formula so it accurately reflects the order of operations. We also need to use the standard math library’s square root method. 1 root1 = (-b + Math.sqrt(b*b - 4*a*c) ) / (2*a); 2 root2 = (-b - Math.sqrt(b*b - 4*a*c) ) / (2*a); Finally, we print the output using System.out.printf() . The full program can be found in Code Sample 26.4. This program was interactive. As an alternative, we could have read all three of the inputs as command line arguments, taking care that we need to convert them to floating point numbers. Lines 16–21 in the program could have been changed to 400"