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20 15 how to solve every 7 questions of science mathematics in Zhejiang college entrance examination? Ask for help
The key to this problem is to express the function value with the formula in brackets. Option a, consider using simultaneous expressions of cos2x = 1-2 sinx 2 and sin2x 2+cos2x 2 = 1, but the expressions on r are not unique and need to be segmented. The mapping from sinx to x in b is not injective (one-to-one correspondence), so it cannot represent the whole R. C makes z = x 2+1,but it cannot match the form of (x+ 1) 2. In D, z = x 2+2x, z+ 1 = (x+ 1) 2, f (z) = root sign (z+ 1) is what you want, so D is the correct answer, and the corresponding f(x)= root sign (.