Question

x的平方+（20-x）的平方=200 如题，算这个方程！

Answer 1

x的平方+（20-x）的平方=200 ==> x^2 + 400 - 40x + x^2 = 200==> 2x^2 - 40x - 200 = 0==> x^2 - 20x -100 = 0==> (x -10)^2 = 200==> |x - 10| = √200==> x =10 ±√200==> x =10 ± 10√2

Answer 2

x的平方+（20-x）的平方=200x^2+400-40x+x^2=200x^2-20x+100=0(x-10)^2=0x-10=0x1=x2=10

Answer 3

x�0�5+（20-x）�0�5=200
x�0�5+400-40x+x�0�5=200
2x�0�5-40x+200=0
x�0�5-20x+100=0
（x-10）（x-10）=0
x1=x2=10

注：倒数第二个是十字相乘法

Answer 4

x^2+(20-x)^2-200=0x^2-20x+100=0(x-10)^2=0x=10

Answer 5

x^2+(20-x)^2=200;
x^2+400-40x+x^2-200=0;
2x^2-40x+200=0;
x^2-20x+100=0;
(x-10)^2=0;
x=10