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

c² + 7c - 18 = 0
(c - 2)(c + 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c - 2) or (c + 9) must equal zero:

If (c - 2) = 0, c must equal 2
If (c + 9) = 0, c must equal -9

So the solution is that c = 2 or -9

A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.

When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

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

-6a + y = -5
y = -5 + 6a

then substitute the result (-5 - -6a) into the second equation:

-5a + 8(-5 + 6a) = 6
-5a + (8 x -5) + (8 x 6a) = 6
-5a - 40 + 48a = 6
-5a + 48a = 6 + 40
43a = 46
a = \( \frac{46}{43} \)
a = 1\(\frac{3}{43}\)

A cylinder is a solid figure with straight parallel sides and a circular or oval cross section with a radius (r) and a height (h). The volume of a cylinder is π r²h and the surface area is 2(π r²) + 2π rh.