Find (fog)(2) and (gof)(-2)

f(x)=Square root of 4-x; g(x)=1-3x^2

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1 answer

f(g) = sqrt(4-g) = sqrt(4-(1-3x^2)) = sqrt(3+3x^2)
f(g(2)) = sqrt(3+12) = sqrt(15)

or, g(2) = 1-12 = -11
f(-11) = sqrt(4+11) = sqrt(15)

do g(f) the same way.