Question

已知a2-ab=3,3ab-b2=4,则多项式2(a2+ab-b2)+a2-2ab+b2的值是

2是平方的意思

Answer 1

2(a2+ab-b2)+a2-2ab+b2
=3a²-b²
=3a²-3ab+3ab-b²
=3(a²-ab)+(3ab-b²)
=3×3+4
=13

Answer 2

2(a^2+ab-b^2)+a^2-2ab+b^2=3a^2-b^2=3(a^2-ab)+3ab-b^2=3*3+4=13

Answer 3

2(a2+ab-b2)+a2-2ab+b2
=2a²＋2ab－2b²＋a²－2ab＋b²
=3a²－b²
=3a²－3ab＋3ab－b²
=3﹙a²－ab﹚＋﹙3ab－b²﹚
=3×3＋4
=13