Question

Multiply the following using appropriate identities.
3. (x + 7) (x + 7)
4. (3x + 1) ( 3x - 8)​

Answer 1

$\Huge\mathfrak\blue{answer:}$

$\bf{~~~~~{\underline{1.~~(x+7)(x+7)}}}$

$\bf{Identity~to~be~used:}$

$\sf{~~~~~~(a+b)(a+b)=a^{2}+2ab+b^{2}}$

$\sf{:→(x)^{2}+2(x)(7)+(7)^{2}}$

$\sf{:→{\blue{\underline{\boxed{\bf x^{2}+14x+49}}}}}$

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$\bf{~~~~~{\underline{2.~~(3x+1)(3x-8)}}}$

$\bf{Identity~to~be~used:}$

$\sf{~~~~~~(x+a)(x+b)=x^{2}+(a+b)x+ab}$

$\sf{:→(x)^{2}+[1+(-8)~]x+[1×(-8)~]}$

$\sf{:→x^{2}+(-7)x+(-8)}$

$\sf{:→{\blue{\underline{\boxed{\bf x^{2}-7x-8}}}}}$