If 7× a number is subtracted from the square of the number the result is 30 find the number
let y = the number
Then y^2 - 7*y = 30
y^2 -7y -30 = 0
(y - 10)(y + 3) = 0
So y = 10 and -3. The -3 make no sense so y = 10
well, you know that x^2 - 7x = 30
so solve that in the usual way
Yikes! Now it makes sense. Problems like this that I usually work I'm looking for a volume or a mass and a mass of -3 g or a volume of -3 cc doesn't make sense. I needed to get in the math bubble to make sense of it. Thanks.
Why did the number go to therapy?
Because it had too many square roots to deal with!
Okay, let's tackle this problem in a humorous way. We're given that when 7 times a number is subtracted from the square of the number, the result is 30.
So, let's call the number "x" and set up the equation:
x^2 - 7x = 30
To make this more entertaining, let's imagine the number as a juggling clown. The clown is juggling numbers and trying to find balance (which in this case is equal to 30). But, oh no, the clown dropped some numbers!
To find the number, we just need to solve the equation:
x^2 - 7x - 30 = 0
Now it's time for some mathematical magic tricks. We'll factor the quadratic equation.
(x - 10)(x + 3) = 0
And just like that, the clown found its numbers! One clown is standing on the number 10 and the other is on -3.
So, the possible numbers could be 10 or -3.
But remember, in mathematics, clowns are tricky! So, check to make sure it satisfies the original condition.
If we substitute 10 into the equation, we get:
10^2 - 7(10) = 100 - 70 = 30
It works! The clown is happy.
But if we substitute -3 into the equation, we get:
(-3)^2 - 7(-3) = 9 + 21 = 30
It works too! The clown is still happy.
Therefore, the number could be 10 or -3.
To solve this problem, we need to set up an equation based on the given information and then solve for the number.
Let's assume the number is represented by "x".
According to the given information:
"The square of the number" can be expressed as x^2.
"7 times the number" can be expressed as 7x.
From the problem, we know that when we subtract "7 times the number" from "the square of the number," the result is 30. Mathematically, this can be written as:
x^2 - 7x = 30
Now, we have a quadratic equation. To solve it, we'll need to bring all terms to one side of the equation by subtracting 30 from both sides:
x^2 - 7x - 30 = 0
This quadratic equation can be factored as follows:
(x - 10)(x + 3) = 0
Setting each factor equal to zero gives us two possible solutions:
x - 10 = 0 --> x = 10
x + 3 = 0 --> x = -3
Therefore, the number can be either 10 or -3.
In conclusion, the number can be either 10 or -3, based on the given equation.
Why reject the 2nd answer, it did not classify the numbers
(-3)^2 - 7(-3)
= 9 + 21
= 30