Question

Zachary purchased a computer for $1,200 on a payment plan. Five months after he purchased the computer, his balance was $525. Seven months after he purchased the computer, his balance was $255. What is an equation that models the balance y after x months?

Answer 1

1200-525= payment after 5 months = 675
675/5 months = 135 paid per month

1200-255 = payment after 7 months = 945
945/7 months = 134 paid per month

y= 1200-134x
because the balance left is 134 less each month after each payment

Answer 2

To solve the quadratic equation x^2 + 6x + 7 = 0, we can use the quadratic formula:

x = (-b ± √(b² - 4ac)) / (2a)

In this equation:

a = 1 (coefficient of x²)

b = 6 (coefficient of x)

c = 7 (constant term)

Now, plug these values into the formula:

x = (-6 ± √(6² - 4 * 1 * 7)) / (2 * 1)

x = (-6 ± √(36 - 28)) / 2

x = (-6 ± √8) / 2

Now, simplify further:

x = (-6 ± 2√2) / 2

We can simplify the fraction by dividing both the numerator and denominator by 2:

x = (-3 ± √2)

So, the solutions to the quadratic equation x^2 + 6x + 7 = 0 are:

x = -3 + √2 (this is one solution)

x = -3 - √2 (this is the other solution)

Explanation:

So, the correct answer is option (c):

x = -3 plus or minus the square root of 2.