Factor the expression below 81a²-25

81a² - 25      

[ax² + bx + c]     Multiply the first and last term (a and c)

81 × 25 = 2025  

Find the factors of 2025 that cancel each other out. [This is because you don't have "bx", and you are trying to find the middle term]

So √2025 = 45       45 multiplied by 45 equals 2025, and they cancel out

Now you can do:

81a² - 45a + 45a - 25   Factor 9a from (81a² - 45a), and factor 5 from (45a - 25)

9a(9a - 5) + 5(9a - 5)      Factor out (9a - 5)

(9a - 5)(9a + 5)

answer: about 22.67

step-by-step explanation:

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.