Answer:
25[tex]x^{4}[/tex] - 49
Step-by-step explanation:
Each term in the second factor is multiplied by each term in the first factor, that is
= 5x²(5x² + 7) - 7(5x² + 7) ← distribute both parenthesis
= 25[tex]x^{4}[/tex] + 35x² - 35x² - 49 ← collect like terms
= 25[tex]x^{4}[/tex] - 49 ← a difference of squares
