There are two numbers whose 400th powers are equal to 9^1000. In other words, there are two numbers that can replace x in the equation
x^400 = 9^1000
making the equation true.
Find the smaller of the two numbers.
1000 / 400 =2.5
9^2.5 =243 =3^5.
So, you can write the first number as:(3^5)^400 = 9^1000 =3^2000 =3^2000
+407 
