arooj1a2b3c

I used to think a Grid-In Answer could never be zero; this question changed my mind.
If (a-10b)^2=a^2+ 100b^2, what is a^2b^4

That just made the PSAT a whole lot harder. Or is it just common sense that if: a -b + c = a + c one would assume that a^2b^4 would be zero?

SerenityJade

(a - 10b)^2 foils to a^2 - 20ab + 100b^2 not a^2 + 100b^2. So a or b must be equal to 0.

If we assume that a = 0 then 0^(2b^4). 0 to any non-zero power is 0.

If we assume b = 0, a^((2*0)^4) = a^(0^4) = a^0 and any non-zero number raised to the 0 power is one. so when b = 0, a^(2b^4) = 1.

So the answer is either 1 or 0. But there's not enough information to know which answer they want.

kimmylouie

Yes PSAT Grid-in allows zeros.

fignewton

A grid-in answer of zero occurred on the May 2011 SAT. But these are very unusual.