If m(x) = x2 + 3 and n(x) = 5x + 9, which expression is equivalent to (mn)(x)?
For this case we have the following functions:
\(m (x) = x ^ 2 + 3
n (x) = 5x + 9\)
Multiplying both functions, we obtain an expression equivalent to (mn) (x).
We have then:
\((mn) (x) = m (x) n (x)\)
Substituting values we have:
\((mn) (x) = (x ^ 2 + 3) (5x + 9)\)
Rewriting the expression we have:
\((mn) (x) = (5x ^ 3 + 15x) + (9x ^ 2 + 27)
(mn) (x) = 5x ^ 3 + 9x ^ 2 + 15x + 27\)
Answer:
An expression that is equivalent to (mn) (x) is:
\((mn) (x) = 5x ^ 3 + 9x ^ 2 + 15x + 27\)
Solution:
It is given that,
\(m(x)=x^2 +3, n(x)=5 x +9\\\\ mn(x)= (x^2+3)(5 x +9)\\\\ m n (x)=x^2\times (5 x +9)+3\times (5 x +9)\\\\ m n(x)=x^2 \times 5 x+x^2\times 9+3 \times 5 x +3 \times 9 \\\\m n(x)=5 x^3+9 x^2+15 x +27\)
The equivalent expression to m n(x) is:
\(1. x(5 x^2+9 x+15)+27\\\\ 2. 5 x^3+3 \times (3 x^2+5x +9) \\\\ 3.5 x^3 +3 x\times (3x +5)+27\)
The Identity used here is
1. Distributive property of multiplication with respect to addition
a × (b+c)= a × b + a × c
2. Law of indices
\(a^m \times a^n=a^{m+n}\)