What polynomial must be added to x^2-2x+6 so that yhe sum is 3x^2+7x?

Do this:
3x² + 7x + 0 -(x² - 2x + 6)
2x² + 9x - 6

2x² + 9x - 6 + x² - 2x + 6 = 3x² + 7x

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .