Answer:
f(x) = 4 - x
Step-by-step explanation:
'f(x) = blah-blah' is the same as saying 'y = blah-blah', except it is also telling you that the x-y relationship is a function.
I notice that for each case, x + y = 4, so y = 4 - x
Or in 'function' terminology, f(x) = 4 - x
Answer:
x = ±
- 3
Explanation:
I'm assuming you want the solutions to that equation, so here goes! (If not, please comment.)
(x-3)(x+9)=27
Let's FOIL this all out and expand. (Remember: First, Outer, Inner, Last.)
x^2 + 9x - 3x - 27
(first+ inner + outer + last)
x^2 + 9x - 3x - 27 = 27
Combine like terms, and add 27 to both sides.
x^2 + 6x - 27 + 27 = 27 + 27
x^2 + 6x = 54
Let's complete the square, because factoring doesn't work, and because it's good practice.
x^2 + 6x + ___ = 54 + ____
In the blank we will put b/2 ^2 = 6/2 ^2 = 3^2 = 9 to complete the square.
x^2 + 6x + 9 = 54 + 9
Now we've got a perfect square factor:
(x + 3)^2 = 63
sqrt(x+3)^2 = 
x + 3 = ± 
x = ±
- 3
Answer:Number of minutes of second Song = 5 1/4 minutes
Number of minutes of third Song =3 1/2 minutes
Step-by-step explanation:
Number of minutes of First Song = 3 1/2 minutes
Number of minutes of second Song = one 1/2 times as long as her first
= 1 1/2 X 3 1/2 minutes
3/2 X 7/2
21/4 = 5 1/4 minutes
Number of minutes of third Song = 2/3 times as long as her second song
2/ 3 x 5 1/4
= 2/3 x 21/4 =42/12
Dividing the numerator and denominator by 3 to reduce the fraction
42/ 12 / 3/3 = 14/4
14/4 = 3 2/4 = 3 1/2 minutes