问题
解答题
解方程组：
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答案
，
=x-4 3
=y+1 4
①z+2 5 x-2y+3z=30②
由①可设
=x-4 3
=y+1 4
=k，z+2 5
x=3k+4，y=4k-1，z=5k-2，
代入方程②得，3k+4-2（4k-1）+3（5k-2）=30，
去括号得，3k+4-8k+2+15k-6=30，
解得k=3，
所以x=3×3+4=13，
y=4×3-1=11，
z=5×3-2=13，
因此，这个方程组的解是
．x=13 y=11 z=13
注意：不改动程序的结构，不是增行或删行。 import java.applet.*; import java.awt.*; import java.awt.event.*; public class Example3_1 extends Applet { int xPoint, yPoint; int sum; Image displayIm; public void init() { displayIm = getImage("ms.jpg"); addMouseListener(new SClickMouse()) ; sum = 2; } public void paint(Graphics g) { if(sum == 1) g.drawImage(displayIm, xPoint, yPoint, this); else g.fillRect(xPoint, yPoint, 60, 60); } public class SClickMouse implements MouseListener { public void mouseClicked(MouseEvent mouse) { sum = mouse.getClickCount(); xPoint = mouse.getX(); yPoint = mouse.getY(); paint(); } public void mouseEntered(MouseEvent mouse) { } public void mouseExited(MouseEvent mouse) {} public void mousePressed(MouseEvent mouse) { xPoint = mouse.getX(); yPoint = mouse.getY(); showStatus("x="+xPoint+",y-"+yPoint); } public void mouseReleased(MouseEvent mouse) } } } } Exampie3_1.html: ＜html＞ ＜head＞＜title＞Example3_1＜/title＞＜/head＞ ＜body＞ ＜applet code="Example3_1.class" width="400" height="500"＞ ＜/applet＞ ＜/body＞ ＜/html＞