x2＋2x-3＝7,则2x2+4x-17=
问题描述：
x2＋2x-3＝7,则2x2+4x-17=
答
x2＋2x-3＝7
x2＋2x＝10
2x2+4x-17
=2（x^2+2x）-17
=2*10-17
=3