Question

factorise by using brain
${25a}^{2} - 4b ^{2} + 28bc - {49c}^{2}$

Answer 1

$25a^{2}-4b^2+28bc-49c^2\\\\25a^2-(4b^2-28bc+49c^2)\\\\25a^2-[(2b-7c)^2]\\\\Here,Using\:the\:Identity : x^2-y^2=(x+y)(x-y)\\\\(5a-2b-7c)(5a+2b-7c)$