(1)计算: 4 - | - 2 | + ( 6 ) 0 - ( - 1 ) .
(2)化简: ( x - 1 ) 2 - x ( x + 7 ) .
已知,如图,AB∥ED,点F、C在AD上,AB=DE,AF=DC.求证:∠B=∠E.
解不等式组:
解方程:x2+4x-3=0;
化简:.
计算: