已知:a2-ab=3,ab-2b2=-1,求a2-3ab+4b2的值
问题描述:
已知:a2-ab=3,ab-2b2=-1,求a2-3ab+4b2的值
答
(a2-ab)-2(ab-2b2)=3-(-1)x2a2-ab-2ab+4b2=3+2a2-3ab+4b2=5
已知:a2-ab=3,ab-2b2=-1,求a2-3ab+4b2的值
(a2-ab)-2(ab-2b2)=3-(-1)x2a2-ab-2ab+4b2=3+2a2-3ab+4b2=5