f（x）f（x）2f（1x）=xf（x）=____x1xf（x）f（1x）535top53top3f（x）g（x）f（x）+g（x）=3x^2-5x-7f（x）g（x）......t......f（x）=-5xg（x）=3x^2-7O（_）O~