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Evaluate [tex](2 - 5i)(p + q)(i)[/tex] when [tex]p = 2[/tex] and [tex]q = 5i[/tex].

A. [tex]29i[/tex]
B. [tex]29i - 20[/tex]
C. [tex]-21i[/tex]
D. [tex]29[/tex]

Sagot :

To evaluate the expression [tex]\((2 - 5i)(p + q)(i)\)[/tex] given that [tex]\(p = 2\)[/tex] and [tex]\(q = 5i\)[/tex], we follow these steps:

1. Substitute the values of [tex]\(p\)[/tex] and [tex]\(q\)[/tex] into the expression [tex]\( (2 - 5i)(p + q) \)[/tex]:

Given:
[tex]\[ p = 2 \][/tex]
[tex]\[ q = 5i \][/tex]

Substitute [tex]\(p\)[/tex] and [tex]\(q\)[/tex] into the expression:
[tex]\[ (2 - 5i)(2 + 5i) \][/tex]

2. Calculate [tex]\((2 - 5i)(2 + 5i)\)[/tex]:

We need to use the distributive property (also known as the FOIL method for binomials) to expand this:
[tex]\[ (2 - 5i)(2 + 5i) = 2 \cdot 2 + 2 \cdot 5i - 5i \cdot 2 - 5i \cdot 5i \][/tex]

Simplify each term:
[tex]\[ = 4 + 10i - 10i - 25i^2 \][/tex]

Recall that [tex]\( i^2 = -1 \)[/tex]:
[tex]\[ = 4 + 10i - 10i + 25 \][/tex]
[tex]\[ = 4 + 25 \][/tex]
[tex]\[ = 29 \][/tex]

3. Multiply the result by [tex]\(i\)[/tex]:

Now we have the intermediate result, [tex]\(29\)[/tex], and we need to multiply this by [tex]\(i\)[/tex]:
[tex]\[ 29 \cdot i = 29i \][/tex]

Thus, the value of [tex]\((2 - 5i)(p + q)(i)\)[/tex] when [tex]\(p = 2\)[/tex] and [tex]\(q = 5i\)[/tex] is [tex]\(\boxed{29i}\)[/tex].