1 Antiderivatives
1.1 Solution 1
\(f(x) = 2x^3 - 9x^2 + 3x - 1\)
Domain: \((-\infty, \infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x f = 2*x^3 - 9*x^2 + (3*x) - 1
octave> octave> f = (sym) 3 2 2⋅x - 9⋅x + 3⋅x - 1
int(f, x)
ans = (sym) 4 2 x 3 3⋅x ── - 3⋅x + ──── - x 2 2
So the antiderivative is \(\dfrac{x^4}{2} - 3*x^3 + \dfrac{3x^2}{2} - 2\) on the interval \((-\infty, \infty)\).
1.2 Solution 2
\(g(x) = \sqrt{x} + \sqrt[3]{x}\)
Domain: \((0, \infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x g = sqrt(x) + (x)^(1/3)
octave> octave> warning: passing floating-point values to sym is dangerous, see "help sym"
warning: called from
double_to_sym_heuristic at line 50 column 7
sym at line 379 column 13
mpower at line 76 column 5
g = (sym)
3 ___
╲╱ x + √x
int(g,x)
ans = (sym) 4/3 3/2 3⋅x 2⋅x ────── + ────── 4 3
Intervals where the antiderivaties apply is same as the original function's domain.
1.3 Solution 3
\(f(x) = \sin x + \cos x\)
Domain: \((-\infty, \infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x f = sin(x) + cos(x) int(f,x)
octave> octave> f = (sym) sin(x) + cos(x) ans = (sym) sin(x) - cos(x)
Intervals where the antiderivaties apply is same as the original function's domain.
1.4 Solution 4
\(g(x) = \sec x(\sec x + \tan x)\)
Let's find the domain of the above function.
We know than \(\sec x = \dfrac{1}{\cos x}\) and \(\tan x = \dfrac{\sin x}{\cos x}\)
So, \(g(x) = \sec^2 x + \sin x \sec^2 x\)
We know the domain of \(\sin x\) is \((-\infty, \infty)\). But domain of \(\sec x\) is \(R - \dfrac{\pi}{2} - n*\pi\)
So the domain of the function \(g(x)\) is \(R - \dfrac{\pi}{2} - n*\pi\).
Let's solve this using GNU Octave:
clear pkg load symbolic syms x g = sec(x)*(sec(x) + tan(x)) int(g,x)
octave> octave> g = (sym) (tan(x) + sec(x))⋅sec(x) ans = (sym) tan(x) + sec(x)
Intervals where the antiderivaties apply is same as the original function's domain.
1.5 Solution 5
\(f(x) = x^2 + \dfrac{1}{x^2}\)
Domain: \((-\infty, 0) \cup (0,\infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x f = x^2 + (1/x^2) int(f,x)
octave> octave> f = (sym)
2 1
x + ──
2
x
ans = (sym)
3
x 1
── - ─
3 x
Intervals where the antiderivaties apply is same as the original function's domain.
1.6 Solution 6
\(g(x) = \dfrac{x^3 + 3}{x^2}\)
Domain: \((-\infty, 0) \cup (0,\infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x g = (x^3 + 3)/(x^2) int(g,x)
octave> octave> g = (sym)
3
x + 3
──────
2
x
ans = (sym)
2
x 3
── - ─
2 x
Intervals where the antiderivaties apply is same as the original function's domain.
1.7 Solution 7
\(f(x) = (x^3 + 3)^2\)
Domain: \((-\infty, \infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x f = (x^3 + 3)^2 int(f,x)
octave> octave> f = (sym)
2
⎛ 3 ⎞
⎝x + 3⎠
ans = (sym)
7 4
x 3⋅x
── + ──── + 9⋅x
7 2
Intervals where the antiderivaties apply is same as the original function's domain.
1.8 Solution 8
\(g(x) = (\dfrac{x^3 + 3}{x})^2\)
Domain: \((-\infty, 0) \cup (0, \infty)\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x g = ((x^3 +3)/x)^2 int(g,x)
octave> octave> g = (sym)
2
⎛ 3 ⎞
⎝x + 3⎠
─────────
2
x
ans = (sym)
5
x 2 9
── + 3⋅x - ─
5 x
Intervals where the antiderivaties apply is same as the original function's domain.
1.9 Solution 9
\(f(x) = sqrt(2x+3)\)
Let's find it's domain:
\(2x + 3 \geq 0\)
\(x \geq \dfrac{-3}{2}\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x f = sqrt(2*x + 3) int(f,x)
octave> octave> f = (sym)
_________
╲╱ 2⋅x + 3
ans = (sym)
3/2
(2⋅x + 3)
────────────
3
Intervals where the antiderivaties apply is same as the original function's domain.
1.10 Solution 10
\(f'(x) = 4x - 3\)
\(f(1) = 4\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x fd(x) = 4*x - 3 int(fd, x)
octave> octave> fd(x) = (symfun) 4⋅x - 3 ans(x) = (symfun) 2 2⋅x - 3⋅x
So the antiderivate is \(2x^2 - 3x + C = F(x)\)
Now let's find the function,
syms c f = 2*x^2 - 3*x + c f_h = function_handle(f) solve(f_h(c, 1) == 4, c)
f = (sym) 2 c + 2⋅x - 3⋅x f_h = @(c, x) c + 2 * x .^ 2 - 3 * x ans = (sym) 5
So the function is \(2x^2 - 3x + 5\)
1.11 Solution 11
\(g'(x) = \sqrt(x) + \sin x\)
\(g(0) = 1\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x gd(x) = sqrt(x) + sin(x) int(gd, x)
octave> octave> gd(x) = (symfun) √x + sin(x) ans(x) = (symfun) 3/2 2⋅x ────── - cos(x) 3
So the antiderivative is \(\dfrac{2*x^{3/2}}{3} - \cos x + c = F(x)\)
Now let's find this function,
syms c f = 2*(x)^(3/2)/3 - cos(x) + c f_h = function_handle(f) solve(f_h(c, 0) == 1, c)
warning: passing floating-point values to sym is dangerous, see "help sym"
warning: called from
double_to_sym_heuristic at line 50 column 7
sym at line 379 column 13
mpower at line 76 column 5
f = (sym)
3/2
2⋅x
c + ────── - cos(x)
3
f_h =
@(c, x) c + 2 * x .^ (3 / 2) / 3 - cos (x)
ans = (sym) 2
So the function is \(\dfrac{2*x^{3/2}}{3} - \cos x + 2 = f(x)\)
1.12 Solution 12
\(f'(x) = \dfrac{1}{\sqrt{x}} + \sec x \tan x\)
\(\lim_{x \to 0^+} f(x) = 2\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x fd(x) = (1/sqrt(x) + sec(x)*tan(x)) int(fd, x)
octave> octave> fd(x) = (symfun)
1
tan(x)⋅sec(x) + ──
√x
ans(x) = (symfun)
1
2⋅√x + ──────
cos(x)
So the antiderivative is \(2\sqrt{x} + \dfrac{1}{\cos x} + c = F(x)\)
Now let's find this function,
syms c f = 2*(x)^(1/2) + (1/cos(x)) + c f_h = function_handle(f) solve(f_h(c,0) == 2)
warning: passing floating-point values to sym is dangerous, see "help sym"
warning: called from
double_to_sym_heuristic at line 50 column 7
sym at line 379 column 13
mpower at line 76 column 5
f = (sym)
1
c + 2⋅√x + ──────
cos(x)
f_h =
@(c, x) c + 2 * sqrt (x) + 1 ./ cos (x)
ans = (sym) 1
So the function is \(2\sqrt{x} + \dfrac{1}{\cos x} + 1 = f(x)\)
1.13 Solution 13
\(g'(x) = x^2 \sqrt[3]{x}\)
\(g(1) = 2\)
Let's solve this using GNU Octave:
clear pkg load symbolic syms x gd(x) = x^2 * x^(1/3) int(gd, x)
octave> octave> warning: passing floating-point values to sym is dangerous, see "help sym"
warning: called from
double_to_sym_heuristic at line 50 column 7
sym at line 379 column 13
mpower at line 76 column 5
gd(x) = (symfun)
7/3
x
ans(x) = (symfun)
10/3
3⋅x
───────
10
So the antiderivative is \(\dfrac{3*x^(10/3)}{10} + c = G(x)\)
Now let's find this function,
syms c g = 3*(x^(10/3))/10 + c g_h = function_handle(g) solve(g_h(c, 1) == 2)
warning: passing floating-point values to sym is dangerous, see "help sym"
warning: called from
double_to_sym_heuristic at line 50 column 7
sym at line 379 column 13
mpower at line 76 column 5
g = (sym)
10/3
3⋅x
c + ───────
10
g_h =
@(c, x) c + 3 * x .^ (10 / 3) / 10
warning: passing floating-point values to sym is dangerous, see "help sym"
warning: called from
double_to_sym_heuristic at line 50 column 7
sym at line 379 column 13
plus at line 61 column 5
eval>@<anonymous> at line 1 column 10
ans = (sym)
17
──
10
So the function is \(\dfrac{3*x^(10/3)}{10} + \dfrac{17}{10} = G(x)\)
1.14 Solution 15
At \(t=0\), we are starting to apply brake. It's also \(h - 0\) and \(a = -10ft/s^2\)
\(h\) is the distance car travelled.
At \(t=t_1\), the car comes to stop.
\(h = 125\) feet
\(f''(t) = a = -10\)
\(f'(t) = -10t + c\)
We need to find \(f'(t)\) at \(t = 0\)
\(h = f(t) = -5*t^2 + c*t + d\)
At \(t=0, h=0\)
\(h = f(0) = d\)
So, \(d = 0\)
At \(t=t_1\), \(h = 125\)
\(h = f(t_1) = -5t_1^2 + ct_1\)
\(125 = -5t_1^2 + ct_1\)
Velocity at \(t_1 = 0\)
\(f'(t_1) = -10t_1 + c = 0\)
\(c = 10*t_1\)
So, \(125 = -5*t_1^2 + 10*t_1^2\)
\(5*t_1^2 = 125\)
\(t_1^2 = 25\)
\(t_1 = 5\)
So velocity at \(t=0\):
\(f'(0) = c = 10t_1 = 10.5 = 50\) feet/s
1.15 Solution 16
At \(t=0\), he applies brakes.
At \(t=2\), he travels 100 feets.
At t=0,
\(f''(t) = a = -10\) feet/s2
\(f'(t) = -10t + c\)
\(f(t) = -5t^2 + ct + d\)
We know that \(f(2) = 100\)
We need to find \(f'(t)\) at \(t = 0\)
We also know that \(f(0) = 0\)
So, \(f(0) = d = 0\)
So, \(d = 0\)
\(f(2) = 100\)
\(-5.2^2 + c.2 + 0 = 100\)
\(-20 + 2c = 100\)
\(2c - 120\)
\(c - 60\)
\(f'(t) = -10t + c\)
\(f'(0) = c = 60\)
So he was going at 60 feet/s when he applied the brakes.
1.16 Solution 17
Initial velocity = 10m/s
Broom acceleration = \(4 m/sec^2\)
Snitch distance = 100 m
Wwe need to find the time to reach snitch
\(a = f''(t) = 4\)
\(f'(t) = 4t + c\)
We know that \(f'(0) = 10\)
\(c = 10\)
\(f'(t) = 4t + 10\)
\(f(t) = 2t^2 + 10t + d\)
We need to find some \(t\) such that \(f(t) = 100\)
We know that at \(t = 0\), \(f(0) = 0\) and \(t = t\), \(f(t) = 100\)
From \(f(0) = 0\), we can conclude that \(d = 0\)
\(f(t) = 100\)
\(2t^2 + 10t = 100\)
\(t^2 + 5t = 50\)
\(t^2 + 5t - 50 - 0\)
So at \(t = 5\) seconds, harry will reach the snitch.
1.17 Solution 18
Tank capacity \(= 500\) Gallon
Water started leaking at noon
At \(t\) minutes after noon, water started leaking at \(5 + 2t\) gallons per miniutes.
\(f(t) = 5 + 2t\)
We need to find at what \(t\), \(f(t)\) becomes \(500\).
\(5 + 2t = 500\)
\(2t = 495\)
\(t = 247.5\)
At \(247.5\) minutes after noon, the tank becomes empty.