2x^3-42x-40=0
2x^3-42x=40
2x(x^2-21)=40
a. 2x=40=>x=20
b. x^2=21+40=>x^2=61=>x=+-(radical(61)
You'll need to isolate 9a on the left side of this equation
Please add 7 to both sides of the eqn, obtaining 9a = 117.
Solve for a by dividing both sides by 9: a = 117/9 = 13 (answer)
Step-by-step explanation:
Suppose a number = A
4(11-A) = 60
(11 - A) = 60/4
11 - A = 15
11 = A + 15
A + 15 = 11
A = 11 - 15
= -4
1. B A C
Reason:
A: 4
is 12.6
B: the Square root of 18.7 is 4.32
2. a
Reason: the square root of 80 is 8.9, thus closest to 9 from all the others.
3. C
Reason: 6/7 = 0.86, and the square root of 3/4 = 0.87