For question b, do you know why you keep it at 1- a and not minus the 1 instead?

Step-by-step explanation &

For 8b, the distance between (2,a) and (5,1) is the square-root of the sum of squares of the difference in x and y directions, namely,

d^2 = ((2-5)^2+(a-1)^2 = 9+a^2-2a+1    (1)

We are given d^2=(sqrt(13)^2)= 13

so by substituting d^2=13, equation (1) becomes

a^2-2a+10=13

a^2-2a-3=0           [simplify]

(a-3)(a+1) = 0          [by factoring]

so a=3 or a=-1

If you have a different approach learned from school, please post what you would have done.  It was not clear in the remark you posted.

Thank you!

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.

me! what did you put for this question?

step-by-step explanation: