Answer:
153.94
Step-by-step explanation:
AB=πr2=π·72≈153.93804
<u>ANSWER:</u>
The solution set for the inequality 7x < 7(x - 2) is null set 
<u>SOLUTION:</u>
Given, inequality expression is 7x < 7 × (x – 2)
We have to give the solution set for above inequality expression in the interval notation form.
Now, let us solve the inequality expression for x.
Then, 7x < 7 × (x – 2)
7x < 7 × x – 2 × 7
7x < 7x – 14
7x – (7x – 14) < 0
7x – 7x + 14 < 0
0 + 14 < 0
14 < 0
Which is false, so there exists no solution for x which can satisfy the given equation.
So, the interval solution for given inequality will be null set
Hence, the solution set is 
Answer:
A. is correct answer
Step-by-step explanation:
full explanation
Step-by-step explanation:
iknow but its hard to expalin
Answer:
30 gallons of 20% acid solution should be mixed.
Step-by-step explanation:
Let x gallons of a 20% acid solution was mixed with 30 gallons of a 40% solution, to obtain a mixture of 30% acid solution.
Therefore, final volume of the solution will be (x + 30) gallons.
Now concept to solve this question is
20%.(x) + 40%.(30) = 30%.(x + 30)
0.20(x) + 0.40(30) = 0.30(x + 30)
0.20x + 12 = 0.30x + 9
0.30x - 0.20x = 12 - 9
.10x = 3
x = 
x = 30 gallons
Therefore, 30 gallons of the 20% acid solution should be mixed.