—And she was the first Chinese who won the prize in science.
A:design
B:thought
C:invention
D:discovery
阅读下列材料:
如果我们规定一种运算为abcd=ad﹣bc,例如:2435=2×5﹣4×3=﹣2,请按照这种运算的规定,解答下列问题:
(1)若51x-32x1x=﹣2,求x的值;
(2)当x满足什么条件时,﹣1<xx-33-2≤4;
若x2+kx+4是一个完全平方式,则常数k的值为( )