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a-7b-8c-4-8a-4b-c-7-a-b-c-R-60-a-2-b-2-c-2-




Question Number 9548 by Joel575 last updated on 14/Dec/16
a − 7b + 8c = 4  8a + 4b − c = 7  a, b, c ∈ R    60(a^2  − b^2  + c^2 ) = ?
a7b+8c=48a+4bc=7a,b,cR60(a2b2+c2)=?
Answered by ridwan balatif last updated on 15/Dec/16
a−7b+8c=4  a+8c=4+7b  (a+8c)^2 =(4+7b)^2   a^2 +16ac+64c^2 =16+56b+49b^2 ...(1)     8a+4b−c=7  8a−c=7−4b  (8a−c)^2 =(7−4b)^2   64a^2 −16ac+c^2 =49−56b+16b^2 ...(2)     (1)+(2)  a^2 +16ac+64c^2 =16+56b+49b^2   64a^2 −16ac+c^2 =49−56b+16b^2   −−−−−−−−−−−−−−−−−−+  65a^2 +65c^2 =65+65b^2   a^2 +c^2 =1+b^2   a^2 −b^2 +c^2 =1  60(a^2 −b^2 +c^2 )=60
a7b+8c=4a+8c=4+7b(a+8c)2=(4+7b)2a2+16ac+64c2=16+56b+49b2(1)8a+4bc=78ac=74b(8ac)2=(74b)264a216ac+c2=4956b+16b2(2)(1)+(2)a2+16ac+64c2=16+56b+49b264a216ac+c2=4956b+16b2+65a2+65c2=65+65b2a2+c2=1+b2a2b2+c2=160(a2b2+c2)=60
Commented by Joel575 last updated on 23/Dec/16
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