Using equations that factor

[lsosa02]

Will someone please help me in this problem . Thank You .

The probem is :Fifteen more than the square of a number is eight times the number .

I tried to set it up , but im not sure if its right : x^2 + 15 = 8x

 

[emmaiskool242]

Will someone please help me in this problem . Thank You .

The probem is :Fifteen more than the square of a number is eight times the number .

I tried to set it up , but im not sure if its right : x^2 + 15 = 8x

you set it up right now you just need to solve it! good luck

 

[stapel]

Looks good to me. Now solve the equation, and check your solution in the original word problem. If your solution works, then it is correct.

Eliz.

 

[lsosa02]

thank you for your help .

But now con you help me start the problem .

 

[stapel]

But now con you help me start the problem.

I'm sorry, but I don't understand. You developed an equation to model the question, and have been provided the steps to the solution, but now you're needing to go back to the beginning and start developing a model...?

Please clarify. Thank you.

Eliz.

 

[skeeter]

I guess you're saying you don't know how to solve a quadratic equation ...

x² + 15 = 8x

get all terms on one side so the quadratic expression = 0 ...

x² - 8x + 15 = 0

factor the quadratic ...

(x - 3)(x - 5) = 0

set each factor equal to 0 and solve for x ...

x - 3 = 0 ... x = 3
x - 5 = 0 ... x = 5

now, check your results with the original problem statement ...

15 more than the square of 3 = 15 + 9 = 24
8 times 3 = 24

15 more than the square of 5 = 15 + 25 = 40
8 times 5 = 40

both solutions check.