Javier estimates the square root of 18 in the following way: √18=2√9=2*3=6 Explain why her reasoning is incorrect. Without using a calculator, the square root of 18 will be between what two values (remember to look for perfect squares/perfect square roots)? Show your reasoning. You do not need to find the decimal equivalent of the root.

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hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!

what i would say the best answer is a. 40.5