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makkiz [27]
3 years ago
5

Identify the interval(s) on which the function y = -x2 + 5x + 14 is positive.

Mathematics
1 answer:
mihalych1998 [28]3 years ago
7 0

Given:

y=-x^2+5x+14

To find:

The interval on which the given function is positive.

Solution:

We have,

y=-x^2+5x+14

Splitting the middle term, we get

y=-x^2+7x-2x+14

y=-x(x-7)-2(x-7)

y=(x-7)(-x-2)

y=-(x-7)(x+2)

Using zero product property, we get

x-7=0\text{ and }x+2=0

x=7\text{ and }x=-2

-2 and 7 divide the number line is three interval.

Interval             Signs of y=-(x-7)(x+2)         Result

(-∞,-2)                             (-)(-)(-)                           Negative    

(-2,7)                              (-)(-)(+)                           Positive    

(7,∞)                               (-)(+)(+)                          Negative    

So, the function is positive for the interval (-2,7), i.e., -2 < x < 7.

Therefore, the correct option is D.

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3/4 of Hari's marbles are black and 1/5 are green. What would be the ratio of black marbles to the green marbles?
Kazeer [188]

Answer:

➩ 15 : 4 is the ratio

Step-by-step explanation:

Hari's marbles are = ¾ which is black in color.

And ⅕ of his marbles are green in color.

Forming in ratio :

\sf \to \:  \frac{3}{4}  : \frac{1}{5}  \\  \sf \to \:  \frac{3}{4}  \times  5 \\  \sf \to \:  \frac{15}{4}  \\  \sf \to \: 15 : 4 \: ans.

4 0
3 years ago
Read 2 more answers
What is 83x8+4-9=<br> POR FAVOR AYUDA
Greeley [361]

Answer:

659

Step-by-step explanation:

664 + 4 - 9 = 659

4 0
3 years ago
Can someone help me answer these two questions? I wanna know what's right and wrong. Please correct me if Necessary
agasfer [191]
Remember that the general equation of a line is y=mx+b, where:
m is the slope, and b is the y-intercept; so to find the y-intercept, solve for y and identify b.
Now, to find the x-intercept, just replace y in your line equation with 0, and solve for x
Lets apply those procedures to our two questions:

1. - y-intercept:
-10x+5y=40
5y=10x+40
y= \frac{10x+40}{5}
y=2x+8
Notice that now we have our line equation in the form y=mx+b with m=2 and b=8; sine b is the y-intercept, we can conclude that the y-intercept of our equation is 8.

x-intercept:
First, lets replace y with 0:
0=2x+8
And then, we can solve for x to find our x-intercept:
2x=-8
x= \frac{-8}{2}
x=-4
We can conclude that our x-intercept is -4; thus the correct answer in your list is the fourth one: x-intercept is -4; y-intercept is 8.

2. y-intercept:
5x+4y=80
4y=-5x+80
y= \frac{-5x+80}{4}
y=- \frac{5}{4} x+20
We can conclude that our y-intercept is 20.

x-intercept:
0=- \frac{5}{4} x+20
- \frac{5}{4} x=-20
x=( \frac{4}{5} )(20)
x=16
We can conclude that our x-intercept is 16; thus the correct answer in your list is, once again, the fourth one: x-intercept is 16; y-intercept is 20.

7 0
3 years ago
Jose has $20 more than Sarah. Their combined mobey totals $90. Write and solve an algebric model to determine the amount of mone
scoray [572]

Let S= the amount of money Sarah has.

Let J= the amount of money Jose has

J= S+20

J+S=90

But we also know that J can equal S+20

So,

S+20+S=90

2S+20=90

2S=70

S=35

So Sarah has $35, and Jose has $35+$20, so he has 55$

6 0
3 years ago
Read 2 more answers
A truck going 50 miles per hour
larisa86 [58]

Answer:

133.33 mph

Step-by-step explanation:

The small trick is to notice the time. Is it 8:00 AM the same day. We don't know, but we will assume it is.

So the truck was on the road for 2 hours.

The car was on the road for 2 - 1/2 = 1 1/2 = 1.5 hours.

The distance travelled was 200 miles

Solution

d = r * t

200 = r * 1.5

200/1.5 = r

r = 133.33 miles / hour

The noise you hear is a siren trying to catch up to the car.

7 0
3 years ago
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