题目内容
计算(1)-12×(-3)-28÷(-7);
(2)(7m2n-5mn)-(4m2n-5mn);
(3)-52-〔23+﹙1-0.8×
)÷(-2)2〕.
(2)(7m2n-5mn)-(4m2n-5mn);
(3)-52-〔23+﹙1-0.8×
| 3 |
| 4 |
(1)-12×(-3)-28÷(-7)
=36+4=40;
(2)(7m2n-5mn)-(4m2n-5mn)
=7m2n-5mn-4m2n+5mn
=3m2n;
(3)-52-[23+(1-0.8×
)÷(-2)2]
=-25-(8+0.1)=-33.1.
=36+4=40;
(2)(7m2n-5mn)-(4m2n-5mn)
=7m2n-5mn-4m2n+5mn
=3m2n;
(3)-52-[23+(1-0.8×
| 3 |
| 4 |
=-25-(8+0.1)=-33.1.
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