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horrorfan [7]
3 years ago
15

Peter is x years old and his sister is 5 years older. If the product of their ages is 84, form an equation in x and solve it to

find peter's age
Mathematics
1 answer:
daser333 [38]3 years ago
3 0

Answer:

x^2 + 5x - 84 = 0

x = 7

Step-by-step explanation:

let the sister's age = y

sister's age (y)  = 5 + x  equation 1

xy = 84  equation 2

Make y the subject of the formula in equation 2

y = 84/x

equate equation 1 and 2

84/x = 5 + x  equation 3

Multiply equation 3 by x

84 = 5x + x^2

x^2 + 5x - 84 = 0

tjis can be solved using quadratic equation

x^2 -7x + 12x -84 = 0

x(x + 12) -7(x + 12)

x = 7 or - 12

age cant be negative so his age is 7

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Step-by-step explanation:

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3 years ago
Estimate . Then record the product 42*6
zhenek [66]
40/5=8

and the answer to your problem is 24

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4 0
3 years ago
A spherical balloon is inflated with gas at the rate of 500 cubic centimeters per minute. How fast is the radius of the balloon
zmey [24]

Using implicit differentiation, it is found that the radius is increasing at a rate of 0.0081 cm per minute.

<h3>What is the volume of a sphere?</h3>

The volume of a sphere of radius r is given by:

V = \frac{4\pi r^3}{3}

Applying implicit differentiation, the rate of change is given by:

\frac{dV}{dt} = 4\pi r^2\frac{dr}{dt}

In this problem, we have that:

\frac{dV}{dt} = 500, r = 70

Hence the rate of change of the radius is given as follows:

\frac{dV}{dt} = 4\pi r^2\frac{dr}{dt}

19600\pi\frac{dr}{dt} = 500

\frac{dr}{dt} = \frac{500}{19600\pi}

\frac{dr}{dt} = 0.0081

The radius is increasing at a rate of 0.0081 cm per minute.

More can be learned about implicit differentiation at brainly.com/question/25608353

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4 0
2 years ago
Is (4,9) a solution to this system of inequalities? y &lt; x + 3 and y &gt; 2x + 1
Setler79 [48]
No

Put (4,9) in equation 1


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7 0
3 years ago
The gradiant y=2x³-5x+1 at point (2,7)​
olga2289 [7]

Given:

The equation of the curve is:

y=2x^3-5x+1

To find:

The gradient (slope) of the given curve at point (2,7).

Solution:

We have,

y=2x^3-5x+1

Differentiate the given equation with respect to x.

y=2(3x^2)-5(1)+(0)

y'=6x^2-5

Now we need to find the value of this derivative at (2,7).

y'_{(2,7)}=6(2)^2-5

y'_{(2,7)}=6(4)-5

y'_{(2,7)}=24-5

y'_{(2,7)}=19

Therefore, the gradient (slope) of the given curve at point (2,7) is 19.

8 0
3 years ago
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