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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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Which two tables represent the same function?
topjm [15]

Answer:

The 1st and the 5th tables represent the same function

Step-by-step explanation:

* Lets explain how to solve the problem

- There are five tables of functions, two of them are equal

- To find the two equal function lets find their equations

- The form of the equation of a line whose endpoints are (x1 , y1) and

  (x2 , y2) is \frac{y-y_{1}}{x-x_{1}}=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}

* Lets make the equation of each table

# (x1 , y1) = (4 , 8) and (x2 , y2) = (6 , 7)

∵ x1 = 4 , x2 = 6 and y1 = 8 , y2 = 7

∴ \frac{y-8}{x-4}=\frac{7-8}{6-4}

∴ \frac{y-8}{x-4}=\frac{-1}{2}

- By using cross multiplication

∴ 2(y - 8) = -1(x - 4) ⇒ simplify

∴ 2y - 16 = -x + 4 ⇒ add x and 16 for two sides

∴ x + 2y = 20 ⇒ (1)

# (x1 , y1) = (4 , 5) and (x2 , y2) = (6 , 4)

∵ x1 = 4 , x2 = 6 and y1 = 5 , y2 = 4

∴ \frac{y-5}{x-4}=\frac{4-5}{6-4}

∴ \frac{y-5}{x-4}=\frac{-1}{2}

- By using cross multiplication

∴ 2(y - 5) = -1(x - 4) ⇒ simplify

∴ 2y - 10 = -x + 4 ⇒ add x and 10 for two sides

∴ x + 2y = 14 ⇒ (2)

# (x1 , y1) = (2 , 8) and (x2 , y2) = (8 , 5)

∵ x1 = 2 , x2 = 8 and y1 = 8 , y2 = 5

∴ \frac{y-8}{x-2}=\frac{5-8}{8-2}

∴ \frac{y-8}{x-2}=\frac{-3}{6}=====\frac{y-8}{x-2}=\frac{-1}{2}

- By using cross multiplication

∴ 2(y - 8) = -1(x - 2) ⇒ simplify

∴ 2y - 16 = -x + 2 ⇒ add x and 16 for two sides

∴ x + 2y = 18 ⇒ (3)

# (x1 , y1) = (2 , 10) and (x2 , y2) = (6 , 14)

∵ x1 = 2 , x2 = 6 and y1 = 10 , y2 = 14

∴ \frac{y-10}{x-2}=\frac{14-10}{6-2}

∴ \frac{y-10}{x-2}=\frac{4}{4}======\frac{y-10}{x-2}=1

- By using cross multiplication

∴ (y - 10) = (x - 2)

∴ y - 10 = x - 2 ⇒ add 2 and subtract y in the two sides

∴ -8 = x - y ⇒ switch the two sides

∴ x - y = -8 ⇒ (4)

# (x1 , y1) = (2 , 9) and (x2 , y2) = (8 , 6)

∵ x1 = 2 , x2 = 8 and y1 = 9 , y2 = 6

∴ \frac{y-9}{x-2}=\frac{6-9}{8-2}

∴ \frac{y-9}{x-2}=\frac{-3}{6}======\frac{y-9}{x-2}=\frac{-1}{2}

- By using cross multiplication

∴ 2(y - 9) = -1(x - 2) ⇒ simplify

∴ 2y - 18 = -x + 2 ⇒ add x and 18 for two sides

∴ x + 2y = 20 ⇒ (5)

- Equations (1) and (5) are the same

∴ The 1st and the 5th tables represent the same function

3 0
3 years ago
Could you guys help me ? I'll give brainliest
ExtremeBDS [4]

When you raise a number to a negative exponent, change the exponent to a positive and make the complete number a fraction with 1 as the numerator.

5 ^-2 = 1/5^2

The answer is C.

4 0
2 years ago
Let f(x) = x^2+ 5x and g(x) = 5 - x. Find f(3) + g(3)​
Alchen [17]

Answer:

26

Step-by-step explanation:

f(x)=x^2+5x g(x)=5‒x

f(3)=3^2+5(3) g(3)=5‒3

f(3)=9+15 g(3)=2

f(3)=24

f(3)+g(3)=24+2

=26

i think it is easy to understand &i hope it helps you

6 0
3 years ago
Can someone please help me :) !!!!
Gwar [14]

Answer:

A

Step-by-step explanation:

supplementary angles add up to 180

angle cgr and kga are vertical angles so they are equal

that makes the two angles in question add up to 180

6 0
3 years ago
Please help!! ill give BRAINLIEST!!!
ella [17]

Answer:

2. x=5.7

4. AC=7

steps :

6 0
3 years ago
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