The sum of a positive number and its square is 20. find the number.

The answer is 4

4 + 16 = 20

So x+x^2=20

subtract 20 from both sdies

x^2+x-20=0

factor

find what 2 nmbers multiply to get - 20 and add to get 1

factors of 20=2 times 2 times 5

the combos are

2 times 10

4 times 5

1 times 20

4 and 5 are 1 in diference

5-4=1

5 times 4=20

(x-4) (x+5) = 0

if xy=0 then x and/or y=0

set each to zero

x-4=0

add 4

x=4

x+5=0

subtract 5

x=-5

but you want positive so this is an extranius answer so discard this

the number is 4