Question

expand (6 - 4a - 7b )^2

Answer 1

$<b>Heya mate. (^_-). Solution below.$
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• (6 - 4a - 7b)²


Let,
a = 6
b = -4a
c = -7b


• Then, using identity :

(a + b + c)²

= a² + b² + c² + 2ab + 2bc + 2ca,


Putting the values of a, b and c,

(6 - 4a - 7b)²

= (6)² + (-4a)² + (-7b)² + {2 × 6 × (-4a)} + {2 × (-4a) × (-7b)} + {2 × (-7b) × 6}

= (36) + (16a²) + (49b²) + (-48a) + (56ab) + (-84b)

= 36 + 16a² + 49b² - 48a + 56ab - 84b

$<marquee>That's your answer.</marquee>$
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Thank you.. ;-)

Answer 2

(a+b+c)*2=
${a}^{2} + {b}^{2} + {c}^{2} + 2ab + 2bc + 2ac$
do according question. =(6-4a-7b)*2. =
${6}^{2} + { - 4a}^{2} + { - 7b}^{2} + 2 \times 6 \times - 4a + 2 \times - 4a + 2 \times - 4a \times - 7b + 2 \times - 6 \times - 7b$
do your self