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inessss [21]
3 years ago
6

If x=-7 is a root of the equation x^2+kx+49=0, then k=​

Mathematics
1 answer:
aleksley [76]3 years ago
8 0

Answer:

k=14

Step-by-step explanation:

Given:

x^{2}+kx+49 = 0

x = -7

Substitution can be used to find the value of k:

(-7)^{2}+(-7)k+49 = 0

49-7k+49 = 0

98 -7k = 0

k = 14

Hope this helps :)

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Michael is taking a survey of students at his high school to find out how many hours they work per week. He surveys all of the s
Fofino [41]

<span>No, he should have surveyed students in his PE class since all grades are represented in that class.</span>
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2 years ago
Read 2 more answers
Hamburger Heaven is having a lunch special where customers buy one 3/4 -pound cheeseburger and get one free. If they set aside 3
user100 [1]

Answer:

49 hamburguers (of 3/4 pound)

Step-by-step explanation:

3/4 pound is equal to 0.75 pound

37 1/3 pounds of meat is equal to

37 + 1/3 pound =  37.3333 pounds

To find how much hamburguers can be made, we need to divide

37.3333 pounds/ 0.75 pounds

37.3333 pounds/ 0.75 pounds = 49.777777

(We need to round to the lowest number)

This means that 49 hamburguers could be made

4 0
3 years ago
Sue has $2.80 in dimes and nickels. If she has 13 more dimes than nickels, how many of each coins does she have?
olga55 [171]
I have seen this question before and I think you meant 10 more dimes than nickels.

We can use substitution to answer this question. The value of a nickel is 5 cents, and we can use the variable n to represent the number of nickels. The value of a dime is 10 cents, and we can use the variable d to represent the number of dimes.

First lets figure out the equations.
.10d+.5n=2.80 (the number of nickels (n) multiplied by .5 will tell us their money value. Same thing for the dimes)
d-n=10 (since there are 13 more dimes than nickels, the number of dimes value (d) minus the number of nickels value (n) will give us 10)

Now lets isolate a variable in one of the equations, preferably the second one because it doesn't have any visible coefficients,

d-n=10
-n=10-d (subtracted the d from both sides)
n=-10+d (made the n positive)

Now that we have the value of n, we can plug it into the other equation.

.10d+.05n=2.80
.10d+.05(-10+d)=2.80 (we replaced the n with the value that we previously got)
.10d-.5+.05d=2.80 (did the multiplication)
.15d-.5=2.80 (combined like terms)
.15d=3.30 (added the .5 to both sides)
d=22 (divided both sides by the .15)

Now that we know that there are 22 dimes and we also know that there are 10 less nickels than dimes, so we can subtract 10 from 22 to get the number of nickels. 22-10=12

d=22
n=12


5 0
3 years ago
Janeel has a 10-inch by 12-inch photograph. She wants to scan the photograph, then reduce the result
Vaselesa [24]

<u>Complete Question:</u>

Janeel has a 10 inch by 12 inch photograph. She wants to scan the photograph, then reduce the results by the same amount in each dimension to post on her Web site. Janeel wants the area of the image to be one eight of the original photograph. Write an equation to represent the area of the reduced image. Find the dimensions of the reduced image.

<u>Correct Answer:</u>

A) (10-x)(12-x)=15

B) Dimensions are : Length = 10-x = 3 inch , Breadth = 12-x = 5 inch

<u>Step-by-step explanation:</u>

a. Write an equation to represent the area of the reduced image.

Let the reduced dimensions is by x , So the new dimensions are

length=10-x\\breadth=12-x

According to question , Area of new image is :

⇒ Area = \frac{1}{8}Length(breadth)

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⇒ Area = 15

So the equation will be :

⇒ (10-x)(12-x)=15

b. Find the dimensions of the reduced image

Let's solve :  (10-x)(12-x)=15

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⇒ 120-22x+x^2=15

⇒ x^2-22x+105=0

By Quadratic formula :

⇒ x = \frac{-b \pm \sqrt{b^2-4ac} }{2a}

⇒ x = \frac{22 \pm8 }{2}

⇒ x = \frac{22 +8 }{2} , x = \frac{22 -8 }{2}

⇒ x = 15 , x =7

x = 15 is rejected ! as 15 > 10 ! Side can't be negative

⇒ x =7

Therefore, Dimensions are : Length = 10-x = 3 inch , Breadth = 12-x = 5 inch

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Answer:

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Step-by-step explanation:

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