Question

(viii) 25a? – 4b2 + 28bc - 49c2
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Answer 1

factories

${5}^{2} - {4b}^{2} + 28bc - {49c}^{2}$

${25a}^{2} - ( {4b}^{2} - 28bc + {49c)}^{2}$

here we get

$( {5a) - (2b)}^{2} - 2 \times 2b \times 7c + ( {7c)}^{2}$

$= {5a }^{2} - ( {2b + {7b}^{2}$

using identities

${x}^{2} - {y}^{2} = (x + y)(x - y)$

$= 5a + (2b - 7c)(5a - (2b - 7c)$

hope it helps you if not I am sorry

Answer 2

Answer:

=25a ² -(4b²-28bc +49c²) = 25a² -( 4b² +49c²+28bc) =25a²-((2b)²+ (7c )²-2×2b×7c) using (×-y ) ²=ײ+y² 2xy here ×=2b and y=7c 25a²-(2b -7c)²