计算.求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-21 求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-22 (-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
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计算.求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-21 求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-22 (-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
计算.求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-2
1 求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-2
2 (-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
计算.求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-21 求-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)的值,其中a=1,b=-22 (-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
解-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)
=-20a^2+4ab-6b^2+15a^2-12ab+9b^2
=-5a^2-8ab+3b^2
由a=1,b=-2
即-5a^2-8ab+3b^2
=-5-8b+3b^2
=-5-8*(-2)+3(-2)^2
=-5+16+12
=23
(-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
=1-(1/2+2/3-3/4-11/12)X24
=1-1/2X24-2/3X24+3/4X24+11/12X24
=1-12-16+18+22
=1-28+18+22
=1-10+22
=13
-2(10a^2-2ab+3b^2)+3(5a^2-4ab+3b^2)
=-20a^2+4ab-6b^2+15a^2-12ab+9b^2
=-20a^2+15a^2+4ab-12ab-6b^2+9b^2
=-5a^2-8ab+3b^2
=-5*1^2-8*1*(-2)+3*(-2)^2
=-5+16+12
=23
(-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
=1-(1/2X24+2/3X24-3/4X24-11/12X24)
=1-(12+16-18-22)
=1-(-12)
=1+12
=13
1.-2(10a²-2ab+3b²)+3(5a²-4ab+3b²)
=-20a²+4ab-6b²+15a²-12ab+9b²
=-5a²-8ab+3b²
=-5×1-8×1×(-2)+3×(-2)²
=-5+16+12
=23
2. (-32)X(-1/32)-(1/2+2/3-3/4-11/12)X24
=1-12-16+18+22
=13