Answer:
≈12.53
Step-by-step explanation:
We know in these kind of triangles that have a 90 degrees angle, we can do:

so the first question:

and then:

so , when you want to rationalize , usually you must multiply the irrational factor as 1:

so , now multiply:

in the next question,we know negative numbers in radical don't have any solution so 2 is correct,
Answer:
.9b+2
Step-by-step explanation:
You first add 3.8b and -2.9b which equals .9b
Then you add -7 and 9 which equals 2
Hope this helped!