derivative of f(x)=(7x^2+7x+7)/(sqrt(x))
We save the definition: f(x) = 7x2 + 7x + 7x
1) Let's perform the differentiation: ddx(7x2 + 7x + 7x)
For p1 = 7x2 + 7x + 7 and q2 = x, use the differentiation rule: ddx(p1q2) = ddx(p1)·q2 -p1·ddx(q2)q22
2) Let's differentiate p1: ddx(7x2 + 7x + 7)
ⓘ The derivative of a sum is the sum of the derivatives: ddx(7x2 + 7x + 7) = ddx(7x2) + ddx(7x) + 0
ddx(7x2) + ddx(7x) + 0
ⓘ A constant factor stays in front of the derivative, (k*u)' = k*u': ddx(7x2) = 7·ddx(x2), ddx(7x) = 7■The derivative of x^n is n*x^(n-1): ddx(x2) = 2x■Adding 0 changes nothing: ddx(7x) + 0 = ddx(7x)
7·2x + 7
ⓘ Multiplications are done before additions and subtractions: 7·2 = 14
14x + 7
3) Let's differentiate q2: ddx(x)
ⓘ The derivative of sqrt(x) is 1/(2*sqrt(x)): ddx(x) = 12x
12x
4) We evaluate the resulting derivative (p1q2)': (14x + 7)·x -(7x2 + 7x + 7)·12x(x)2
ⓘ Multiplying a fraction by a term multiplies its numerator: (7x2 + 7x + 7)·12x = (7x2 + 7x + 7)·12x = 7x2 + 7x + 72x■To add fractions, put them over the same denominator, then add the numerators: (14x + 7)·x -7x2 + 7x + 72x = (14x + 7)·x·2x -(7x2 + 7x + 7)2x■A power of a power multiplies the exponents, (a^n)^m = a^(n*m): (x)2 = x12·2
(14x + 7)·x·2x -(7x2 + 7x + 7)2xx12·2
ⓘ A minus sign before a parenthesis changes the sign of each of its terms: -(7x2 + 7x + 7) = -7x2 -7x -7■Multiplying powers with the same base adds the exponents: x·x = x■Multiplying a fraction by a number multiplies its numerator: 12·2 = 1·22 = 22■We simplify the fraction by dividing the numerator and the denominator by 2, their greatest common divisor: 22 = 1
2·(14x + 7)·x -7x2 -7x -72xx1
2·(14x + 7)·x -7x2 -7x -72xx
ⓘ Dividing a fraction by x is multiplying its denominator by x: 2·(14x + 7)·x -7x2 -7x -72xx = 2·(14x + 7)·x -7x2 -7x -72x·x
2·(14x + 7)·x -7x2 -7x -72x·x
ⓘ Multiplying powers with the same base adds the exponents: xx = x12 + 1
2·(14x + 7)·x -7x2 -7x -72x12 + 1
ⓘ To add fractions, put them over the same denominator, then add the numerators: 12 + 1 = 1 + 22
2·(14x + 7)·x -7x2 -7x -72x1 + 22
ⓘ The numerator and the denominator are computed before the division: 1 + 2 = 3
2·(14x + 7)·x -7x2 -7x -72x32
ⓘ Expand by multiplying each term inside the parentheses: 2·(14x + 7) = 28x + 14
(28x + 14)·x -7x2 -7x -72x32
ⓘ Expand by multiplying each term inside the parentheses: (28x + 14)·x = 28x2 + 14x
28x2 + 14x -7x2 -7x -72x32
ⓘ Like terms are grouped by adding their coefficients: 28x2 -7x2 = 21x2, 14x -7x = 7x
21x2 + 7x -72x32
5) Then you can resume the differentiation:
ⅰ ddx(7x2 + 7x + 7x) = 21x2 + 7x -72x32
▶Derivative:   21x2 + 7x -72x32