The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(1²) + 2π(1 x 7)
sa = 2π(1) + 2π(7)
sa = (2 x 1)π + (2 x 7)π
sa = 2π + 14π
sa = 16π

The entire length of this line is represented by AD which is AB + BD:

AD = AB + BD

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

2a + 4a = 6a

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

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 + 4y - 44 = 5y - 2
y² + 4y - 44 + 2 = 5y
y² + 4y - 5y - 42 = 0
y² - y - 42 = 0

Next, factor the quadratic equation:

y² - y - 42 = 0
(y + 6)(y - 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y + 6) or (y - 7) must equal zero:

If (y + 6) = 0, y must equal -6
If (y - 7) = 0, y must equal 7

So the solution is that y = -6 or 7