Question

1.已知x-y=4,x的平方-y的平方=20,则x+y=（ ）

Answer 1

1.5 x的平方-y的平方=(x+y)(x-y)x+y=20/4=52.=(m^2-4n^2)^2=m^4-8乘以m的平方乘以n的平方+16n^43.4.004.=(1+1/2)(1-1/2)(1+1/3)(1-1/3)(1+1/4)(1-1/4)=(1+1/2)(1+1/3)(1+1/4)(1-1/2)(1-1/3)(1-1/4)=(3/2 * 4/3 * 5/4...