Question

If a-b=7 ab=9 then what is the value of a^2-b^2

Answer 1

$\longrightarrow\sf{a^2-b^2=(a+b)(a-b)}$

$\longrightarrow\sf{a^2-b^2=7\sqrt{(a+b)^2}}$

$\longrightarrow\sf{a^2-b^2=7\sqrt{a^2+2ab+b^2}}$

$\longrightarrow\sf{a^2-b^2=7\sqrt{a^2-2ab+b^2+4ab}}$

$\longrightarrow\sf{a^2-b^2=7\sqrt{(a-b)^2+4ab}}$

$\longrightarrow\sf{a^2-b^2=7\sqrt{7^2+4\times9}}$

$\longrightarrow\sf{a^2-b^2=7\sqrt{49+36}}$

$\longrightarrow\sf{\underline {\underline {a^2-b^2=7\sqrt{85}}}}$