Let p(x)=90/9+50e^−x. What is p(−2)?

Enter your answer, rounded to the nearest tenth, in the box.

p(x) = 90 / (9 + 50 * e^(-x))

e = 2.718, so we can use e = 2.7 as a quick substitute

p(3) =>

90 / (9 + 50 * e^(-3)) =>

90 / (9 + 50 * 2.7^(-3)) =>

90 / (9 + 50 / 2.7^3) =>

90 / ((9 * 2.7^3 + 50) / 2.7^3) =>

90 * 2.7^3 / (9 * 2.7^3 + 50)

2.7^3 =>

(27/10)^3 =>

27^3 / 1000 =>

729 * 27 / 1000 =>

2187 * 9 / 1000 =>

6561 * 3 / 1000 =>

19683 / 1000 =>

19.683

90 * 2.7^3 / (9 * 2.7^3 + 50) =>

90 * 19.683 / (9 * 19.683 + 50)

9 * 19.683 =>

9 * (20 - 0.317) =>

180 - 9 * 0.317 =>

180 - 9 * 0.3 - 9 * 0.017 =>

180 - 2.7 - 9 * 0.01 - 9 * 0.007 =>

177.3 - 0.09 - 0.063 =>

177.3 - 0.153 =>

177.15 - 0.003 =>

177.147

90 * 19.683 / (9 * 19.683 + 50) =>

10 * 177.147 / (177.147 + 50) =>

1771.47 / 227.147 =>

1771470 / 227147 =>

1770000 / 225000 =>

1770/225 =>

4 * 1770 / 900 =>

4 * 177 / 90 =>

708/90 =>

70.8 / 9 =>

23.6 / 3 =>

(21 + 2.6) / 3 =>

7 + 0.866666 =>

7.8666666...

Actual value:  7.8333389811057471507345888320992

Not bad for some estimates, is it?