Question

Number 18 pls help me

Answer 1

Lila did it correctly. The answer is 324

Following PEMDAS, we first focus on the parenthesis. So we simplify 9-3 to get 6

So we go from 
18*4^2+(9-3)^2 
to 
18*4^2+6^2 

The next step is applying exponents. In this case, squaring the terms, so we go from
18*4^2+6^2 
to
18*16+36

Next is multiplying
18*16+36
turns into
288+36

Finally, add up 288 and 36 to get 288+36 = 324

That confirms that Lila is correct

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The error that Rob made is that he computed 18*4^2+9^2-3^2 but it is NOT correct. Saying (x-y)^2 = x^2-y^2 isn't a true equation for all x and y. Again you have to simplify what is in the parenthesis first, and then you can square it. Or you must use the FOIL rule to expand out (9-3)^2