please help i dont understand this

PROBLEM 1-

Let $A(t) = 3- 2t^2 + 4^t$. Find $A(2) - A(1)$.

PROBLEM 2-

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PROBLEM 3-

Find all values of $s$ such that $(s + 4)(s - 3) \le 0$. Give your answer as an interval.

PROBLEM 4-

Find all values of $t$ such that $8t^2 \le 3-10t$. Give your answer in interval notation.

PS: sorry about problem 2, my image files were glitching so I had to put it as a link