To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(7a)(3ab) + (7a²)(7b)
(7 x 3)(a x a x b) + (7 x 7)(a² x b)
(21)(a¹⁺¹ x b) + (49)(a²b)
21a²b + 49a²b
70a²b

A cube is a rectangular solid box with a height (h), length (l), and width (w). The volume is h x l x w and the surface area is 2lw x 2wh + 2lh.

The formula for circumference is circle diameter x π:

c = πd
c = 14π

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 4 x 1) + (2 x 1 x 7) + (2 x 4 x 7)
sa = (8) + (14) + (56)
sa = 78

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

y² + 14y + 13 = 5y - 1
y² + 14y + 13 + 1 = 5y
y² + 14y - 5y + 14 = 0
y² + 9y + 14 = 0

Next, factor the quadratic equation:

y² + 9y + 14 = 0
(y + 2)(y + 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y + 2) or (y + 7) must equal zero:

If (y + 2) = 0, y must equal -2
If (y + 7) = 0, y must equal -7

So the solution is that y = -2 or -7