Let's see what to do buddy...
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Reminder:
[tex](a + b)(a - b) = {a}^{2} - {b}^{2} [/tex]
So we need to just Multiply above equations like this :
[tex]x + y = 70[/tex]
[tex]x - y = 40[/tex]
[tex](x + y)(x - y) = 70 \times 40[/tex]
[tex] {x}^{2} - {y}^{2} = 2800 [/tex]
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And we're done.
Thanks for watching buddy good luck.
♥️♥️♥️♥️♥️
