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.

5a⁸ - 7a⁸ = -2a⁸

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

r = \( \frac{d}{2} \)
r = \( \frac{10}{2} \)
r = 5
a = πr²
a = π(5²)
a = 25π

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

-4a + z = -3
z = -3 + 4a

then substitute the result (-3 - -4a) into the second equation:

5a - 4(-3 + 4a) = 4
5a + (-4 x -3) + (-4 x 4a) = 4
5a + 12 - 16a = 4
5a - 16a = 4 - 12
-11a = -8
a = \( \frac{-8}{-11} \)
a = \(\frac{8}{11}\)

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the < sign and the answer on the other.

5a + 5 < -2 + 4a
5a < -2 + 4a - 5
5a - 4a < -2 - 5
a < -7

According to the Pythagorean theorem, the hypotenuse squared is equal to the sum of the two perpendicular sides squared:

c² = a² + b²
c² = 8² + 7²
c² = 64 + 49
c² = 113
c = \( \sqrt{113} \)