math problems!!!!!!!!!!!!!!!!! help please?

Question

pg189
#5

using each of the digits 2 through 5 only once, write 2 two-digit whole numbers whose product is as large as possible.

#6

using each of the digits 3 through 8 only once, write 2 three-digit whole numbers whose product is as large as possible.

#8

the cube of a whole number is 48 more than the square of the same number. what is the number?

pg 193 #1b
solve. use the method of completeing the square.

m^2= -6m-7


please show the work thank you!!!!!!!!!!

Answer 1

#5
52 * 43 = 2 236

#6
853 * 764 = 651 692
864 * 753 = 651 692

Answer 2

5)

52 x 43 = 2236

I did this by first maximizing the digit in the tens column.

6) 853 x 764 = 651692 (Using the same method)

8) x^3 = x^2 + 48

x = 4

9) Completing the square method:

m^2 = -6m-7

m^2 + 6m = -7

m^2 + 6m + 9 = -7 +9

(m + 3)^2 = -2

m+ 3 = sqrt -2

m = -3 +/- i sqrt 2

This answer is "negative three plus or minus "i" times the square root of 2"

Answer 3

52*43
864*753
4 is the number.

4^3=64. 4^2=16.

I don't remember how to complete the square.

Answer 4

#6 is 4
4*2=16
4*3=64
64-16=48

I think #8 is m=6i*2-7i*2
not %100 though