The formula for circumference is circle diameter x π. Circle diameter is 2 x radius:

c = πd
c = π(2 * r)
c = π(2 * 11)
c = 22π

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 - 5y + 8 = 2y - 2
y² - 5y + 8 + 2 = 2y
y² - 5y - 2y + 10 = 0
y² - 7y + 10 = 0

Next, factor the quadratic equation:

y² - 7y + 10 = 0
(y - 2)(y - 5) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y - 2) or (y - 5) must equal zero:

If (y - 2) = 0, y must equal 2
If (y - 5) = 0, y must equal 5

So the solution is that y = 2 or 5

You need to find the value of a so solve the first equation in terms of x:

-a + x = -6
x = -6 + a

then substitute the result (-6 - -1a) into the second equation:

6a + 3(-6 + a) = 2
6a + (3 x -6) + (3 x a) = 2
6a - 18 + 3a = 2
6a + 3a = 2 + 18
9a = 20
a = \( \frac{20}{9} \)
a = 2\(\frac{2}{9}\)

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.

7a² + 6a² = 13a²

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

sa = 2πr² + 2πrh
sa = 2π(6²) + 2π(6 x 2)
sa = 2π(36) + 2π(12)
sa = (2 x 36)π + (2 x 12)π
sa = 72π + 24π
sa = 96π