She used 54 inches. 3/4 is equal to .75 so you can find 3/4 of the board by taking the fool length and multiplying it by .75 so 6•.75=4.5. So 3/4 of the board is 4.5 ft. However, the answer has to be in inches so since there are 12 inches in a foot you multiply 4.5•12 and that gives you your answer:54 inches.
We can factor by grouping. To do so, we multiply the leading coefficient with the constant at the end. In other words, a times c (ax^2 + bx + c).
15*-4 = -60
Now we need to split the b term into two pieces that multiply to -60 and add to 4.
-6 and 10 will work.
Now group one part of b with the 15x^2 and the other part with -4.
(15x^2 + 10x) + (-6x - 4)
Now factor both terms.
5x(3x+2) - 2(3x+2)
3x+2 is one of our factors and 5x-2 is the other.
(3x+2)(5x-2)=0
Now just find the zeros.
3x+2 = 0
3x = -2
x = -2/3
And
5x-2 = 0
5x = 2
x = 2/5
So the answer is x = -2/3 and x = 2/5
Answer:
c. t = 18; the Chang family has been driving for 18 hours
Step-by-step explanation:
Given:
D(t) = 2,280 - 60t
Find t when D(t) = 1,200
D(t) = 2,280 - 60t
1200 = 2280 - 60t
Subtract 2280 from both sides of the equation
1200 - 2,280 = 2280 - 60t - 2,280
- 1080 = - 60t
Divide both sides by -60
- 1080 / -60 = - 60t / -60
18 = t
t = 18
This means the Chang family has been driving for 18 hours
c. t = 18; the Chang family has been driving for 18 hours
