5. Let E be an extension of F and let a, b E E. Prove that F(a, b) = F(a)(b) = F(b)(a).

I need step by step explan

Let's say the countdown for a space shuttle launch has begun. At "T minus 25 hours" (that is, 25 hours before launch), a problem occurs. If the technicians have not fixed the problem by T minus 8 hours, the launch will have to be scratched. How much time (in hours) do the technicians have to correct the problem? hr

The total weekly sales for a newly released portable media player (PMP) increased each week. At the same time, the total weekly sales for another newly released PMP decreased each week. Models that approximate the total weekly sales S (in thousands of units) for each PMP are = 10x + 70 S = = -10x + 210 where x represents the number of weeks each PMP was in stores, with x = 0 corresponding to the PMP sales on the day each PMP was first released in stores. After how many weeks will the sales for the two PMPs be equal? 11 weeks 5 weeks 3 weeks 9 weeks PMP 1 PMP2 7 weeks