f(4)= 4^2 - 1 = 15
g(f(4)) = g(15) = 2(15) = 30
Hope this helps!
Answer:
39.6
Thirty nine point six
Step-by-step explanation:
9 x 4 2/5
9 x 22/5
198/5 = 39.6
Thirty nine point six
Answer:
Two solutions (-4,-7) and (4,7)
Step-by-step explanation:
x = y + 3
x*y = 28
(y+3)*y=28
y^2+3y-28=0
(y+7)(y-4)=0
y=-7, y=4
x=-4, x=7
Answer:
- The system of equations is x + y = 85 and 7/20x+2/5y=31
- To eliminate the x-variable from the equations, you can multiply the equation with the fractions by 20 and multiply the other equation by -7.
- B-She used 60 minutes for calling and 25 minutes for data.
Step-by-step explanation:
It is always a good idea to start by defining variables in such a problem. Here, we can let x represent the number of calling minutes, and y represent the number of data minutes. The the total number of minutes used is ...
x + y = 85
The total of charges is the sum of the products of charge per minute and minutes used:
7/20x + 2/5y = 31.00
We can eliminate the x-variable in these equations by multiplying the first by -7 and the second by 20, then adding the result.
-7(x +y) +20(7/20x +2/5y) = -7(85) +20(31)
-7x -7y +7x +8y = -595 +620 . . . . eliminate parentheses
y = 25 . . . . . . . . simplify
Then the value of x is
x = 85 -y = 85 -25
x = 60
