1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
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

You might be interested in
If DF=7x-3 and EG=5x+9, find the value of X
PilotLPTM [1.2K]

Answer:

x=6

Step-by-step explanation:

Using the given measurements of the angles and the lengths of the sides, we can determine that this figure must be a <u>rectangle</u>.

Diagonals of a rectangle are <em>always</em> equivalent/congruent.

We can use this information to set up an equation:

DF=EG\\7x-3=5x+9

Add 3 to both sides:

7x-3+3=5x+9+3\\7x=5x+12

Subtract 5x from both sides:

7x-5x=5x-5x+12\\2x=12

Divide both sides by 2

\frac{2x}{2}=\frac{12}{2}\\x=6

3 0
2 years ago
6(2) - 7(8 + 6 - 3(2)​
san4es73 [151]

Answer:

-44

Step-by-step explanation:

12-7(8+6-6)

12-7(8)

12-56

-44

7 0
3 years ago
Read 2 more answers
Help me please (#20) I need this by tomorrow
Rama09 [41]

Answer:

the third one

Step-by-step explanation:

7 0
3 years ago
Read 2 more answers
ann pays 300 for membership to a local gym. she is allowed to bring one guest on any visit. John pays Ann 5 to go to the gym wit
klemol [59]

Answer:

The expression represents Ann's membership cost as a function of how many times she brings John along. For t = 5 the cost is 275, for t = 10, the cost is 250 and for t = 20 the cost is 200.

Step-by-step explanation:

The expression "300 - 5*t" represents the cost of Ann's membership plan on the local gym, where "t" is the number of visits John pays Ann. This means that the more times John goes to the gym with Ann, the less is her cost to pay the membership.

For t = 5:

cost = 300 - 5*t\\cost = 300 - 5*5 = 275

For t = 10:

cost = 300 - 5*t\\cost = 300 - 5*10 = 250

For t = 20:

cost = 300 - 5*t\\cost = 300 - 5*20 = 200

5 0
3 years ago
Which one would it be and why.
SVETLANKA909090 [29]

Answer:B because its the rule in algebra that you must gave 1 as a zero

Step-by-step explanation:

5 0
3 years ago
Other questions:
  • A school has two wings each of which is a rectangle or prism the school district is planning to instill air conditioning in the
    5·1 answer
  • Witch of the following could be a horizontal cross-section of a cylinder
    15·1 answer
  • Which of these expressions is equivalent to 3(5x − 2)?
    15·2 answers
  • If the probability of p(m and n) =0.2 p(m)=0.4 and m and independent events, what is p(n)?
    6·1 answer
  • 1. Let f(x) = 5x + 3 and g(x) = 3x<br> What is (f + g)(x)?
    11·1 answer
  • A student solved z + (-0.72) = -2.5 for z using the following steps.
    11·2 answers
  • I need help it's due tomorrow​
    12·2 answers
  • Bob has a recipe for salad dressing. The recipe says to mix 1/4 cup lemon juice, some mustard, and some vinegar to make a total
    10·2 answers
  • What does it mean to find the value of a numerical or algebraic expression?
    7·1 answer
  • A fuelling vehicle finished filling a plane with 12.40 tons of fuelat 10:35. If the fuelling rate is 0.20 ton of fuel per min, a
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!