The original (which is wrong) has 2x<sup>3</sup>+bx<sup>2</sup>-5x+20.
Another version going around has 2x<sup>3</sup>+bx<sup>2</sup>-2x+20 (also wrong).
The correct version has 2x<sup>3</sup>+bx<sup>2</sup>+2x+20.
This third version is available at http://4unitmaths.com/sydney-tech-ext2-2014.pdf
Another version going around has 2x<sup>3</sup>+bx<sup>2</sup>-2x+20 (also wrong).
The correct version has 2x<sup>3</sup>+bx<sup>2</sup>+2x+20.
This third version is available at http://4unitmaths.com/sydney-tech-ext2-2014.pdf