How i solve the question of class 9th math of Polynomials chapter of Exercise 2.5 of math of question no.4 give me the best way for solving this question how i solve this question Expand each of the following, using suitable identities:(iv) (3a –7b–c)2
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Expand each of the following, using suitable identities:(iv) (3a –7b–c)2 Q.4(4)
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Using identity (x+y+z)2 = x2+y2+z2+2xy+2yz+2zx
Here, x = 3a
y = – 7b
z = – c
(3a –7b– c)2 = (3a)2+(– 7b)2+(– c)2+(2×3a ×– 7b)+(2×– 7b ×– c)+(2×– c ×3a)
= 9a2 + 49b2 + c2– 42ab+14bc–6ca