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Evaluate the expression [tex]a^2 + 12abc - c^2[/tex] for [tex]a = -8[/tex], [tex]b = 6[/tex], and [tex]c = 7[/tex].

A. [tex]\(-4017\)[/tex]
B. [tex]\(4047\)[/tex]
C. [tex]\(-3919\)[/tex]
D. [tex]\(-4145\)[/tex]


Sagot :

To solve the expression [tex]\(a^2 + 12abc - c^2\)[/tex] given the values [tex]\(a = -8\)[/tex], [tex]\(b = 6\)[/tex], and [tex]\(c = 7\)[/tex], let's go through the steps in detail.

1. Square of [tex]\(a\)[/tex]:

Calculate [tex]\(a^2\)[/tex]:
[tex]\[ a = -8 \implies a^2 = (-8)^2 = 64 \][/tex]

2. Product of 12, [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:

Calculate [tex]\(12 \cdot a \cdot b \cdot c\)[/tex]:
[tex]\[ a = -8, \, b = 6, \, c = 7 \implies 12 \cdot (-8) \cdot 6 \cdot 7 \][/tex]

3. Calculation of the term [tex]\(12abc\)[/tex]:

First, calculate [tex]\( (-8) \cdot 6 = -48 \)[/tex].

Then, multiply the result by [tex]\( 7 \)[/tex]:
[tex]\[ -48 \cdot 7 = -336 \][/tex]

Finally, multiply by 12:
[tex]\[ 12 \cdot (-336) = -4032 \][/tex]

4. Square of [tex]\(c\)[/tex]:

Calculate [tex]\(c^2\)[/tex]:
[tex]\[ c = 7 \implies c^2 = 7^2 = 49 \][/tex]

5. Combine all parts:

Substitute these values back into the expression:
[tex]\[ a^2 + 12abc - c^2 = 64 + (-4032) - 49 \][/tex]

6. Simplify the expression:

Combine [tex]\(64\)[/tex], [tex]\(-4032\)[/tex], and [tex]\(-49\)[/tex]:
[tex]\[ 64 - 4032 - 49 \][/tex]

7. Final Calculation:

Performing the subtraction step-by-step:
[tex]\[ 64 - 4032 = -3968 \][/tex]
[tex]\[ -3968 - 49 = -4017 \][/tex]

Therefore, the value of the expression [tex]\(a^2 + 12abc - c^2\)[/tex] for [tex]\(a = -8\)[/tex], [tex]\(b = 6\)[/tex], and [tex]\(c = 7\)[/tex] is [tex]\(-4017\)[/tex]. This matches our required answer.

Thus, the correct answer is:
[tex]\[ \boxed{-4017} \][/tex]