Question

a. Multiply 7/4 X 9/10 and explain all your steps.b. Multiply n/(n-3) X 9/(n+3) and explain all your steps.c. Evaluate your answer to part (b) when n=7 . Did you get the same answer you got in part (a)? Why or why not?

Answer 1

Solution:

A) Part A asked to multiply

Concept:

$\frac{a}{b}\times\frac{c}{d}=\frac{a\times c}{b\times d}=\frac{ac}{bd}$

By applying the concept, we will have

$\begin{gathered} \frac{7}{4}\times\frac{9}{10} \\ =\frac{7\times9}{4\times10}=\frac{63}{40} \end{gathered}$

Hence,

The answer to part A is = 63/40

Part B:

The part b asked to multiply

$\frac{n}{(n-3)}\times\frac{9}{(n+3)}$

By applying the concept above, we will have

$\begin{gathered} \frac{n}{(n-3)}\times\frac{9}{(n+3)} \\ =\frac{n\times9}{(n-3)(n+3)} \\ =\frac{9n}{n(n+3)_{}-3(n+3)} \\ =\frac{9n}{n^2+3n-3n-9} \\ =\frac{9n}{n^2-9} \end{gathered}$

Therefore,

The answer to the multiplication of part B is

$\frac{9n}{n^2-9}$

Part C:

Evaluate your answer to part (b) when n=7

Substitute the value of n=7 in the expression below

$\begin{gathered} \frac{9n}{n^2-9},n=7 \\ =\frac{9(7)}{7^2-9} \\ =\frac{63}{49-9} \\ =\frac{63}{40} \end{gathered}$

The answer to part c is = 63/40

The answer is the same as the answer gotten in part a BECAUSE ON SUBSTITUTING THE VALUE OF n=7 IN THE ANSWER IN PART B the same answer was gotten..