501,883 views
3 votes
3 votes
The product 8 and the square of a number decreased by 5 is 67. Find the number.

User Abdallah Okasha
by
2.2k points

1 Answer

19 votes
19 votes

Answer:

3 or -3

Step-by-step explanation:

Let's call the unknown number x. The square of this number is x². The product of 8 and the square of this number is 8x². Finally, it is decreased by 5, so 8x² - 5 and it is equal to 67, then the equation that represents the statement is:

8x² - 5 = 67

Now, we can solve the equation for x. Add 5 to both sides

8x² - 5 + 5 = 67 + 5

8x² = 72

Divide both sides by 8

8x²/8 = 72/8

x² = 9

Find the square root of both sides

x = √9

x = 3 or x = -3

Therefore, the number is 3 or -3

User Hong Van Vit
by
2.8k points