Answer:
- 81t² + 16
Explanation:
Simply expand the equation by factoring
(9t-4)(-9t-4) factor out negative sign
= -(9t - 4) (9t +4)
= -(9t + 4) (9t - 4) recall a² - b² = (a+b) (a-b)
= - [ (9t)² - 4²]
= - ( 81t² - 16)
= - 81t² + 16
2) -81t² +16
(9t -4)(-9t -4) = (9t x -9t) + (9t x -4) + (-4 x -9t) + (-4 x -4)
= -81t² - 36t + 36t + 16
= -81t² + 16
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