已知A=6a²-6ab-2B
已知A=6a²-6ab-2B,B=﹣4a²+5ab+6。若a-1绝对值加(b+2)²=0.求A的值快快……要过程
la-1l (b+2)2=0
a-1=0
a=1
b 2=0
b=-2
A=6a2-6ab-2(﹣4a2+5ab+6)
=6a2-6ab 8a2-10ab-12
=14a2-16ab-12
=14x12-16x1x(-2)-12
=14 32-12
=34
,,
因为 ? |a-1| (b 2)^2=0, ? ?所以 a-1= 0,且 b 2=0, ? ?a=1, b=-2,
B= -4a^2 5ab 6 = -4*1^2 5*1*(-2) 6=-4-10 6=-8
A= 6a^2-6ab-2B=6*1^2 - 6*1*(-2)-2(-8)=6 12 16=34
望采纳
已知A=6a2?6ab?2B,B=?4a2 5ab 6。若|a?1| (b 2)2=0.求A的值
解:|a?1|≥0,(b 2)2≥0
当|a?1| (b 2)2=0时,因0 0 0,必
? ?|a?1|=0,(b 2)2=0
? ?|a?1|=0,a=1
? ?(b 2)2=0,b=?2,得
A=6a2?6ab?2B
A=6a2?6ab?2(?4a2 5ab 6)
=14a2?16ab?12
=32
∵∣a-1∣ (b 2)2=0
∴a-1=0 ?b 2=0
则a=1,b=-2
当a=1,b=-2时,
B=-4a2 5ab 6
? =-4×12 5×1×(-2) 6
? =-4-10 6
? =-8
则A=6a2-6ab-2B
? ? ?=6×12-6×1×(-2)-2×(-8)
? ? ?=6 12 16
? ? ?=34
答:已知:A-2B=7a的平方-7ab,且B=-4a的平方+6ab+7 1.求A等于多少? A=7a²-7ab+2B =7a²-7ab+2(-4a²+6ab+7) ...详情>>
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