This is a quadratic formula with a general form of a²x + bx + c = 0. For quadratic equations, we can solve for its two roots using the quadratic formula shown in the attached picture.
a = -3
b = -4
c = -4
x = [-(-4) + √(-4)² - 4(-3)(-4)]/2(-3) =
<em>2 + √-32/2</em>x = [-(-4) - √(-4)² - 4(-3)(-4)]/2(-3) =
<em> 2 - √-32/2</em>
d = 3 , a₁₂ = 40 and S
= 7775
In an arithmetic sequence the nth term and sum to n terms are
<h3>• a

= a₁ + (n-1)d</h3><h3>• S

=

[2a + (n-1)d]</h3><h3>
where d is the common difference</h3><h3>a₆ = a₁ + 5d = 22 ⇒ 7 + 5d = 22 ⇒ 5d = 15 ⇔ d = 3</h3><h3>a₁₂ = 7 + 11d = 7 +( 11× 3) = 7 + 33 = 40</h3><h3>S₁₀₀ =

[(2×7) +(99×3)</h3><h3> = 25(14 + 297) = 25(311)= 7775</h3>
Rewrite as (2^1/2 + 2^1/2)*(18^1/2-2^1/2) = 8