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

6b + x = -5
x = -5 - 6b

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

-9b + 2(-5 - 6b) = -8
-9b + (2 x -5) + (2 x -6b) = -8
-9b - 10 - 12b = -8
-9b - 12b = -8 + 10
-21b = 2
b = \( \frac{2}{-21} \)
b = -\(\frac{2}{21}\)

The Pythagorean theorem defines the relationship between the side lengths of a right triangle. The length of the hypotenuse squared (c²) is equal to the sum of the two perpendicular sides squared (a² + b²): c² = a² + b² or, solved for c, \(c = \sqrt{a + b}\)

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 8 x 7) + (2 x 7 x 2) + (2 x 8 x 2)
sa = (112) + (28) + (32)
sa = 172

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

b² + b - 42 = 0
(b - 6)(b + 7) = 0

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

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

So the solution is that b = 6 or -7

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.

4a⁷ + 2a⁷ = 6a⁷