= 3x² - 5x + 4 + 5x² + 7x - 8= (3x² + 5x²) + (-5x + 7x) + (4 - 8)= 8x² + 2x - 4
Therefore, the simplified expression is 8x² + 2x - 4.
= 3x² - 5x + 4 + 5x² + 7x - 8
= (3x² + 5x²) + (-5x + 7x) + (4 - 8)
= 8x² + 2x - 4
Therefore, the simplified expression is 8x² + 2x - 4.