Get reliable answers to your questions at Westonci.ca, where our knowledgeable community is always ready to help. Join our Q&A platform to connect with experts dedicated to providing precise answers to your questions in different areas. Connect with a community of professionals ready to help you find accurate solutions to your questions quickly and efficiently.

what multiplies to equal negative 90 but adds to be negative one

Sagot :

The numbers are 10 and -9. Since the product is negative, that implies that one number is negative and the other positive. Since the sum is 1, we know that the two numbers have to be close in magnitude. The most logical choice was 10 and -9. 

Or, you could set up and solve two equations: 

x + y = 1 

xy = -90 

Solve the first for x, 

x = 1 - y 

Substitute into the second, 

(1 - y)y = -90 

y - y² = -90 

y² - y - 90 = 0 

Factor 

(y - 10)(y + 9) = 0 

The roots are 10 and -9 

If y = 10, then x = 1 - y = -9 

We know that pair works. 

If y = -9, then x = 1 - y = 10 

That pair works, also.