(1)
(2)
(3)
(4)﹣14+6×[2﹣(﹣3)2]
(5)(2x+3y)﹣3(x﹣5y)
(6)先化简再求值:a2﹣2(ab+b2)﹣2(a2﹣ab﹣3b2),其中a=1,.
解:(1)原式=5.4+0.75﹣10.4+0.25,
=5.4﹣10.4+1,
=﹣4;
(2),
=(﹣+﹣)×60,
=(﹣)×60,
=﹣10;
(3),
=﹣27×2+5×3×3,
=﹣54+45,
=﹣9;
(4)﹣14+6×[2﹣(﹣3)2],
=﹣1+6(2﹣9),
=﹣1﹣42,
=﹣43;
(5)(2x+3y)﹣3(x﹣5y),
=2x+3y﹣3x+15y,
=﹣x+18y;
(6)a2﹣2(ab+b2)﹣2(a2﹣ab﹣3b2),
=a2﹣2ab﹣2b2﹣2a2+2ab+6b2,
=a2﹣2b2﹣2a2+6b2,
=﹣a2+4b2,
当a=1,时,
原式=﹣12+4×(﹣)2=0.
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