1)平方得(ma)^2+2mab+b^2=3a^2-6mab+3(mb)^2a,b的模均为2,且a^2=|a|^2=4,b^2=|b|^2=4故4m^2+2mab+4=12-6mab+12m^28mab=8m^2+8ab=m+1/m (m>0)2)基本不等式ab>=2,当m=1>0时取等号当ab=|a||b|cosA=2时,|a|=|b|=2,(A表是...