Java Reference
In-Depth Information
T
EST
Q
UESTIONS
P
ROGRAMMING
E
XERCISES
Pedagogical Note
For each exercise, carefully analyze the problem requirements and design strategies for
solving the problem before coding.
think before coding
Debugging Tip
Before you ask for help, read and explain the program to yourself, and trace it using
several representative inputs by hand or using an IDE debugger. You learn how to
program by debugging your own mistakes.
learn from mistakes
Section 3.2
*3.1
(
Algebra: solve quadratic equations
) The two roots of a quadratic equation
ax
2
+
bx
+
c
=
0 can be obtained using the following formula:
b
2
b
2
r
1
=
-
b
+ 2
-
4
ac
r
2
=
-
b
- 2
-
4
ac
and
2
a
2
a
b
2
4
ac
is called the discriminant of the quadratic equation. If it is positive, the
equation has two real roots. If it is zero, the equation has one root. If it is negative,
the equation has no real roots.
Write a program that prompts the user to enter values for
a
,
b
, and
c
and displays
the result based on the discriminant. If the discriminant is positive, display two
roots. If the discriminant is
0
, display one root. Otherwise, display “The equation
has no real roots”.
Note that you can use
Math.pow(x, 0.5)
to compute
-
2
x
. Here are some
sample runs.
Enter a, b, c: 1.0 3 1
The equation has two roots -0.381966 and -2.61803
Enter a, b, c: 1 2.0 1
The equation has one root -1
Enter a, b, c: 1 2 3
The equation has no real roots
3.2
(
Game: add three numbers
) The program in Listing 3.1, AdditionQuiz.java, gen-
erates two integers and prompts the user to enter the sum of these two integers.
Revise the program to generate three single-digit integers and prompt the user to
enter the sum of these three integers.
Search WWH ::
Custom Search