What two number multiply to -21 and add to 20

-1 and 21

Step-by-step explanation:

Let the numbers be x and y.

x + y = 20

xy = -21

Solve the first equation for x and substitute in the second equation.

x = 20 - y

(20 - y)y = -21

20y - y^2 = -21

y^2 - 20y - 21 = 0

(y - 21)(y + 1) = 0

y - 21 = 0 or y + 1 = 0

y = 21 or y = -1

For y = 21:

x = 20 - y

x = 20 - 21

x = -1

For y = -1:

x = 20 - y

x = 20 - (-1)

x = 21

Solutions: (-1, 21) and (21, -1)

the numbers are -1 and 21

126.66 m²

step-by-step explanation:

the pertinent area formula is a = πr², where r is the radius.

here, a = π(6.35 m)² = 40.32π, or approximately 126.66 m²

answer is 8x+24

area of vanessa's patio = length × width

given, length = (3x² + 5x + 10)

width = (x² - 3x - 1)

area of vanessa's patio = (3x² + 5x + 10)(x² - 3x - 1)

= 3x²(x² - 3x - 1) + 5x(x² - 3x - 1) + 10(x² - 3x - 1)

= 3x⁴ - 9x³ - 3x² + 5x³ - 15x² - 5x + 10x² - 30x - 10

= 3x⁴ - 4x³ - 8x² - 35x - 10

hence, expression of vanessa's patio = (3x⁴ - 4x³ - 8x² - 35x - 10)