Question

please solve this question (-3a + 7b -c )square .it is a brainlest question

Answer 1

This problem can be rewritten as:

(
3
a
−
7
b
)
(
3
a
−
7
b
)


To multiply these two terms you multiply each individual term in the left parenthesis by each individual term in the right parenthesis.

(
3
a
−
7
b
)
(
3
a
−
7
b
)
becomes:

(
3
a
×
3
a
)
−
(
3
a
×
7
b
)
−
(
7
b
×
3
a
)
+
(
7
b
×
7
b
)

9
a
2
−
21
a
b
−
21
a
b
+
49
b
2


We can now combine like terms:

9
a
2
+
(
−
21
−
21
)
a
b
+
49
b
2


9
a
2
−
42
a
b
+
49
b
2
hope it will help....
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Answer 2

Hola Mate !!

Here's your answer :-

${(a + b + c)}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2ab + 2bc + 2ca$

Now, substituting the above formula in the equation :

${(( - 3a) + 7b + ( - c))}^{2} \\ = > {( - 3a)}^{2} + {(7b)}^{2} + { ( - c)}^{2} + 2 \times - 3a \times 7b + 2 \times 7b \times - c + 2 \times - c \times - 3a \\ = > 9 {a}^{2} + 49 {b}^{2} + {c}^{2} - 42ab - 14bc + 6ac$

Hope it helps