挑战习题
1/5单选题
难度:

1.下列多项式是二次三项式的是()
A a2+b2
B x+y+7
C 5-x-y2
D x2-y2+x-y
提示1:
5aSa6aG55byP5qyh5pWw5Y+K6aG555qE5qaC5b+1
正确答案:Qw==
5aSa6aG55byP6YeM77yM5qyh5pWw5pyA6auY6aG555qE5qyh5pWw77yM5Y+r5YGa5aSa6aG55byP55qE5qyh5pWw77yb5q+P5Liq5Y2V6aG55byP5Y+r5YGa5aSa6aG55byP55qE6aG544CC5pWF6YCJQ+OAgg==