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:

x² - 8x - 4 = -x + 4
x² - 8x - 4 - 4 = -x
x² - 8x + x - 8 = 0
x² - 7x - 8 = 0

Next, factor the quadratic equation:

x² - 7x - 8 = 0
(x + 1)(x - 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (x + 1) or (x - 8) must equal zero:

If (x + 1) = 0, x must equal -1
If (x - 8) = 0, x must equal 8

So the solution is that x = -1 or 8

To factor a quadratic expression, apply the FOIL (First, Outside, Inside, Last) method in reverse.

The area of a parallelogram is equal to its length x width:

a = l x w
a = a x b
a = 3 x 6
a = 18

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

y² - 10y + 9 = 0
(y - 1)(y - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y - 1) or (y - 9) must equal zero:

If (y - 1) = 0, y must equal 1
If (y - 9) = 0, y must equal 9

So the solution is that y = 1 or 9

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

-7a + y = -6
y = -6 + 7a

then substitute the result (-6 - -7a) into the second equation:

-7a + 4(-6 + 7a) = -8
-7a + (4 x -6) + (4 x 7a) = -8
-7a - 24 + 28a = -8
-7a + 28a = -8 + 24
21a = 16
a = \( \frac{16}{21} \)
a = \(\frac{16}{21}\)