Question

已知:A-2B=7a05,且B=-4a05+6ab+7. (1)求A等于多少? (2)若|a+1|+(b-2)²=0，求A的值。

Answer 1

A=7a²+2(-4a²+6ab+7)=7a²-8a²+12ab+14=-a²+12ab+14

若|a+1|+(b-2)²=0
a+1=0 a=-1
b-2=0 b=2

A=-a²+12ab+14=-(-1)²-12x1x2+14=-1-24-14=-11

Answer 2

A-2B=7a²
A=2B+7a²=2(-4a²+6ab+7)+7a²
=-8a²+12ab+14+7a²
=-a²+12ab+14

2、
a+1=0
b-2=0
∴a=-1
b=2
∴A=-1-24+14=-11