174k views
2 votes
The square of a positive number is 24 more than 5 times a number. What is the value of the number?

User Vincenza
by
8.9k points

2 Answers

2 votes

Answer: The positive number is
8.


Step-by-step explanation: Let, the positive number to find be
x. Then, its square will be
x^(2). Sicne
x^2 is
24 more than
5x, so, while forming an algebraic equation from the given information, we will write


x^(2) -24=5x\\\Rightarrow x^(2) -5x-24=0\\\Rightarrow x^(2) -8x+3x-24=0\\\Rightarrow x(x-8)+3(x-8)=0\\\Rightarrow (x-8)(x+3)=0,

which gives


x-8=0\Rightarrow x=8

and


x+3=0\Rightarrow x=-3.

Since the given number is positive, so
x=-3 cannot be true. Hence,
x=8 is the solution.

Thus, the positive number is
8.


User Donparalias
by
7.9k points
2 votes
First, let's construct an algebraic equation to formally find the answer:

Let x represent (the value of) the unknown number.

x²= 5x + 24 --- This equation shows that the (positive) number's square equals 24 more than 5 times the number.

Now we can solve for x (the number):

x² = 5x + 24
x² - 5x - 24 = 0
(x + 3)(x - 8) = 0
x = -3, 8

Therefore, this means that x (the number ) can be either -3 OR 8. Both will satisfy the description.
Hope this helps!
User Karusmeister
by
7.6k points