七年级上册有理数混合运算专题精选练习 下载本文

(2)﹣÷(﹣)×(﹣1)=﹣÷=20+36 =56.

30.计算:

×(﹣1)+4×9

42015

+(﹣2)×(﹣3)

22

(1)6+(﹣8)+9﹣(+11)﹣|﹣4| (2)(3)(4)(5)(6)(7)(8)

【解答】解:(1)6+(﹣8)+9﹣(+11)﹣|﹣4| =6﹣8+9﹣11﹣4 =(6+9)﹣(11+4)﹣8 =15﹣15﹣8 =﹣8; (2)

=﹣2﹣17﹣10+9+4﹣7 =﹣16﹣7 =﹣23;

(3)=﹣

×8×

×

=﹣13; (4)

=﹣81÷×÷16 =﹣81×××=﹣1; (5)

=﹣1﹣××(2﹣9) =﹣1﹣×(﹣6) =﹣1+1 =0; (6)=(﹣20+=120﹣ =119; (7)=(﹣

+

)×(﹣6)

﹣)×(﹣42)

×(﹣42)+

×(﹣42)﹣×(﹣42)

=×(﹣42)﹣=﹣12+10﹣9+12 =1 (8)=[

﹣(×36﹣

×36+×36)]÷(﹣14)

=[=(=﹣=﹣

﹣(28﹣33+6)]÷(﹣14) ﹣1)×(﹣×