1.

Evaluate : `(i) (a+6b)^(2) " " (ii) (3x-4y)^(2) " " (iii) (2a-b+c)^(2)`

Answer» (i) `(a+6b)^(2)=a^(2)+2xxaxx6b+(6b)^(2)=a^(2)+12ab+36b^(2)`
`(ii) (3x-4y)^(2)=(3x)^(2)-2xx3x xx4y+(4y)^(2)=9x^(2)-24xy+16y^(2)`
`(iii) " We know that " (x+y+z)^(2)=x^(2)+y^(2)+z^(2)+2xy+2yz+2zx`
Now, `(2a-b+c)^(2)=(2a)^(2)+(-b)^(2)+(c )^(2)+2{(2a)(-b)xxc+cxx(2a)}`
`=4a^(2)+b^(2)+c^(2)-4ab-2bc+4ac`


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