Which expression is equivalent to x4 + 4x² – 45?

Step-by-step explanation:

x4 + 4x² – 45 = x^4 + 4x^2 - 45.  Use " ^ " to indicate exponentiation.

Temporarily substitute p for x^2.  Then we have:

p^2 + 4p - 45, or

(p + 9)(p - 5)

But p = x^2.

Therefore, our expression becomes

(x^2 + 9)(x^2 - 5)

We could stop here or we could factor further.  

Hint:  x^2 - 5 = (x - √5)(x + √5); (x^2 + 9) factors into imaginary roots.

answer: city needs 2.4 inches of rainfall more to match the record of 40 inches.

step-by-step explanation:

since we have given that

total annual rainfall a city record = 40 inches

this year, total rainfall recorded = 37.6 inches

number of inches of rainfall   is needed to match the record of 40 inches is given by

hence, city needs 2.4 inches of rainfall more to match the record of 40 inches.