Integrating with shells is the easier method.
<em>V</em> = 2<em>π</em> ∫₁³ <em>x</em> (√<em>x</em> + 3<em>x</em>) d<em>x</em>
That is, at various values of <em>x</em> in the interval [1, 3], we take <em>n</em> shells of radius <em>x</em>, height <em>y</em> = √<em>x</em> + 3<em>x</em>, and thickness ∆<em>x</em> so that each shell contributes a volume of 2<em>π</em> <em>x</em> (√<em>x</em> + 3<em>x</em>) ∆<em>x</em>. We then let <em>n</em> → ∞ so that ∆<em>x</em> → d<em>x</em> and sum all of the volumes by integrating.
To compute the integral, just expand the integrand:
<em>V</em> = 2<em>π</em> ∫₁³ (<em>x </em>³ʹ² + 3<em>x</em> ²) d<em>x</em>
<em>V</em> = 2<em>π</em> (2/5 <em>x </em>⁵ʹ² + <em>x</em> ³) |₁³
<em>V</em> = 2<em>π</em> ((2/5 ×<em> </em>3⁵ʹ² + 3³) - (2/5 × 1⁵ʹ² + 1³))
<em>V</em> = 4<em>π</em>/5 (9√3 + 64)
Answer:
+ 3x² - 4
Step-by-step explanation:
Note that complex zeros occur in conjugate pairs
If 2i is a zero then - 2i is a zero
The zeros are x = 1, x = - 1, x = 2i, x = - 2i, thus the factors are
(x - 1), (x + 1), (x - 2i) and (x + 2i)
The polynomial is expressed as the product of the factors, thus
f(x) = (x - 1)(x + 1)(x - 2i)(x + 2i) ← expanding in pairs
= (x² - 1)(x² - 4i²) → i² = - 1
= (x² - 1)(x² + 4) ← distribute
= + 4x² - x² - 4
= + 3x² - 4
Knowing the slope and a point
of a line, the equation of the line is given by
Substitute your values to get
You can rearrange this equation to write it in the slope-incercept form: