A:狩猎文明
B:游牧文明
C:农耕文明
D:工业文明
设两个一元二次方程ax2+2bx+1=0和cx2+2dx+1=0(其中a,b,c,d均为实数)满足a+c=2bd.求证:上述两个方程中至少有一个方程有实数根.
— In addition, you and I have lots of things in common.
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看图填一填。
____个十和____个一合起来是____
59添上1是____个十,是____