You need to find the value of c so solve the first equation in terms of z:

4c + z = 7
z = 7 - 4c

then substitute the result (7 - 4c) into the second equation:

-7c + 1(7 - 4c) = -1
-7c + (1 x 7) + (1 x -4c) = -1
-7c + 7 - 4c = -1
-7c - 4c = -1 - 7
-11c = -8
c = \( \frac{-8}{-11} \)
c = \(\frac{8}{11}\)

The volume of a cylinder is πr²h:

v = πr²h
v = π(6² x 4)
v = 144π

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 + 3a = 5a

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

x² - 5x + 6 = 0
(x - 2)(x - 3) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (x - 2) or (x - 3) must equal zero:

If (x - 2) = 0, x must equal 2
If (x - 3) = 0, x must equal 3

So the solution is that x = 2 or 3

The formula for area is πr². Radius is circle \( \frac{diameter}{2} \):

r = \( \frac{d}{2} \)
r = \( \frac{6}{2} \)
r = 3
a = πr²
a = π(3²)
a = 9π