Question

expand (2a-7b-5c)² please answer
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Answer 1

(a+b+c)²=a²+b²+c²+2ab+2bc+2ca

(2a+(-7b)+(-5c) )² = 4a²+49b²+25c²+2.2a.-7b+2.-7b.-5c+2.-5c.2a

=> 4a²+49b²+25c²-28ab+70bc-20ac

i hope its correct !