Official papers

Official 2019 Paper 2 · Q20

Paper 2Logic & proofFunctions & graphs

When the graph of the function y=f(x)y=f(x), defined on the real numbers, is reflected in the yy-axis and then translated by 2 units in the negative xx-direction, the result is the graph of the function y=g(x)y=g(x).

When the graph of the same function y=f(x)y=f(x) is translated by 2 units in the negative xx-direction and then reflected in the yy-axis, the result is the graph of the function y=h(x)y=h(x).

Which one of the following conditions on y=f(x)y=f(x) is necessary and sufficient for the functions g(x)g(x) and h(x)h(x) to be identical?

Af(x)=f(x+2)f(x)=f(x+2) for all xx
Bf(x)=f(x+4)f(x)=f(x+4) for all xx
Cf(x)=f(x+8)f(x)=f(x+8) for all xx
Df(x)=f(−x)f(x)=f(-x) for all xx
Ef(x)=f(2−x)f(x)=f(2-x) for all xx
Ff(x)=f(4−x)f(x)=f(4-x) for all xx
Gf(x)=f(8−x)f(x)=f(8-x) for all xx

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