Idon’t get how the answer is one..
not sure how to factor/reduce what i was able to reduce to equal 1

did i do something wrong

see explanation

Step-by-step explanation:

Factorise the numerators on both fractions

a² + 10a + 25 = (a + 5)(a + 5) ← perfect square

a² - 25 = (a - 5 )(a + 5) ← difference of squares

To divide, leave the first fraction, change division to multiplication and turn the second fraction upside down.

Hence

= ×

Cancel both the (a + 5) factors on the numerator/ denominators and the (a - 5) factor on the numerator/denominator, leaving

= 1 ← as required

step-by-step explanation:

for the free