Factorize a² +3ab - 5ab - 15b².

Step-by-step explanation:

Work via factoring by groups:

!) re arrange the terms as follows:

then extract the common factor for the first two terms (a), and separately the common factors for the last two terms (3 b):

Now notice that the binomial factor (a-5 b) is in both expressions, so extract it:

which is the final factorization.

Step-by-step explanation:

she played for 18.75 hours.

step-by-step explanation:

if she played 2/4 of a hour on tuesday. and there is 60 minutes in an hour and 60 divided by 4 is 7.5. and she played 2/4 of an hour on thursday then again 60 divided by 4 is 7.5, you add 7.5+7.5=56.25. now you have to do 1/4 of an hour, it equals 3.75. now you have to add them all up. 3.75+7.5+7.5=18.75

i hope this and i hope you get it right. it took me a while to get this done for you. : )

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is: