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3 years ago

Prove that for any natural n the value of the expression (n+7)^2–n^2 is divisible by 7.

Mathematics

1 answer:

Afina-wow [57]3 years ago

3 0

Step-by-step explanation:

(n + 7)² – n²

n² + 14n + 49 – n²

14n + 49

7 (2n + 7)

7 is a factor, so for any natural n, (n + 7)² – n² is a multiple of 7.

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Click here please. The problems are in picture format

padilas [110]

First picture:

You got the first two right (good job!), so I'll just tackle the third one. If you have to compute $f(x-4)$ , it means that you have to substitute $x-4$ in place of $x$ . Differently from the first two points, this will generate a new function, rather than a specific value:

$f(x) = \sqrt{x+4}+2 \implies f(x-4) = \sqrt{(x-4)+4}+2 = \sqrt{x}+2$

Second picture:

Given the point $(x,y)$ highlighted in the picture, you can deduce that the base is $2x$ units long (since it spans from $(-x,0)$ to $(x,0)$ ) and the height is $y$ units long (because it spans from $(x,0)$ to $(x,y)$ ). So, the area of the rectangle is the multiplication between base and height:

$A = 2xy$

But we know that $y=f(x)=\sqrt{36-x^2}$ , so we have

$A = 2x\sqrt{36-x^2}$

The domain of this function is given by the domain of the square root: we want its argument to be non, negative, so we have

$36-x^2 \geq 0 \iff x^2 \leq 36 \iff -6 \leq x \leq 6$

But since the problem is symmetric, the answer is

$0 \leq x \leq 6$

You can only see the answer $0 < x < 6$ because, if you choose $x=0$ or $x=6$ , the rectangle degenerates to a segment, and your exercise doesn't like this scenario, apparently

4 0

3 years ago

carlos and Jacob each improve their yards by planting daylilies and ivy. They bought their supplies from the same stores. Carlos

34kurt

Answer:

Cost of each daylilies = $3

Cost of each ivy pot = $3

Step-by-step explanation:

Given:

Cost of 4 daylilies and 4 ivy = $24

Cost of 4 daylilies and 8 ivy = $36

Find:

Cost of each daylilies

Cost of each ivy pot

Computation:

Assume;

Cost of each daylilies = a

Cost of each ivy pot = b

So,

4a + 4b = 24....... eq 1

4a + 8b = 36 ....... eq 2

Eq2 - Eq1

8b - 4b = 36 - 24

4b = 12

b = 3

So,

Cost of each ivy pot = $3

4a + 4b = 24

4a + 4(3) = 24

4a + 12

a = 3

Cost of each daylilies = $3

6 0

2 years ago

Solve for x:

pentagon [3]

Answer:

2<x<3

Step-by-step explanation:

4x-4<8 AND 9x+5>23

Solve the first inequality

4x-4<8

Add 4 to each side

4x-4+4 <8+4

4x<12

Divide by 4

4x/4 <12/4

x <3

Solve the second inequality

9x+5>23

Subtract 5 from each side

9x+5-5>23-5

9x >18

Divide by 9

9x/9>18/9

x>2

Put together

x<3 and x>2

2<x<3

3 0

2 years ago

Jamal wrote the following statements:

Marat540 [252]

<span>A is the correct answer. In geometry, postulate is something that is assumed to be true without proof being given. In contrast, a theorem is a true statement which can be proven. A definition defines or explains what a term means. Statement one is a definition of perpendicular lines and statement two can be proven. </span>

6 0

3 years ago

PLEASEE HELP.!! ILL GIVE BRAINLIEST.!! *EXTRA POINTS* DONT SKIP:((

Serhud [2]

B I might be wrong cause i can’t tell if that’s B but the 3rd box

3 0

2 years ago