Factor the following expression.

19. Which expression is equivalent to [tex]$210d^2 - 63d$[/tex]?

A. [tex]21d(10d - 3)[/tex]
B. [tex]21(10d + 3)[/tex]
C. [tex]21d(10d + 3)[/tex]
D. [tex]3 \cdot 21(10d - 3)[/tex]



Answer :

To factor the expression [tex]\(210d^2 - 63d\)[/tex], follow these steps:

1. Identify Common Factors:
Examine the coefficients (210 and 63) and the variable for common factors:
[tex]\[ 210 = 2 \times 3 \times 5 \times 7 \][/tex]
[tex]\[ 63 = 3 \times 3 \times 7 \][/tex]
The common factors of 210 and 63 are [tex]\(3 \times 7 = 21\)[/tex].
The common variable factor is [tex]\(d\)[/tex].

2. Factor Out the GCD:
Since both terms share a common factor of [tex]\(21d\)[/tex], we can factor that out:
[tex]\[ 210d^2 - 63d = 21d(10d) - 21d(3) \][/tex]

3. Factor Each Term:
When the common factor [tex]\(21d\)[/tex] is factored out, distribute it across the remaining terms:
[tex]\[ 21d(10d - 3) \][/tex]

Therefore, the factored form of [tex]\(210d^2 - 63d\)[/tex] is:

[tex]\[ 21d(10d - 3) \][/tex]

So, the correct answer is:

[tex]\[ \boxed{21d(10d - 3)} \][/tex]

This corresponds to option F in the given choices.