Martha is following a recipe for 13 liters of punch that uses 8 liters of pineapple juice and the rest lemonade.
How much pineapple juice is used for every liter of lemonade? What is the ratio of liters of pineapple juice to liters of punch ?

For every 1 liter of lemonade Martha has to add 1.6 liters of pineapple juice.

The ratio of liters of pineapple juice to liters of punch is 8:13

Step-by-step explanation:

13 - 8 = 5

5 divided by 5 is 1

8 divided by 5 is 1.6

step-by-step explanation:   divide the numerator by the denominator to get the decimal

it would still be 193

if divide by 100 then 1.93

i am not sure

x^2 + 81

we can factor this using difference of square binomials.

rewrite the equation:

x^2 - (-81)

factor:

(a^2 - b^2) = (√a^2 + √b^2)(√a^2 - √b^2)

(x^2 - (-81) = (x + √-81)(x - √-81)

we can remove the - from under the radical by multiplying it by i.

(x^2 - (-81) = (x + i√81)(x - i√81)

(x^2 - (-81) = (x + 9i)(x - 9i)

we can check our answer by using foil:

x^2 - 9ix + 9ix - 81i^2

x^2 - 81^2

i^2 = -1

x^2 + 81