If f (x-1) = 1 + lgx, then f (9)=______ ．

If f (x-1) = 1 + lgx, then f (9)=______ ．

∵ f (x-1) = 1 + lgx, then f (9) = 1 + LG10 = 2, so the answer is: 2

If a and B are the two roots of equation 2 (lgx) ^ 2-2lgx-3 = 0, find a and B

Let lgx = t (T > 0)
Then it is transformed into 2T ^ 2-2t-3 = 0
T1 = (1 + radical 7) / 2 T2 = (1-radical 7) / 2

The number of elements in point set {(x, y) | LG (X3 + 3 / Y3 + 9 / 1) = lgx + lgY} is（
The number of elements in point set {(x, y) | LG (X3 + Y3 of 3 + 1 of 9) = lgx + lgY} is () a.0 B.1 C.2 D. more than 2

X3 + Y3 of 3 + 1 of 9 > = 3 open cube (x ^ 3 * y ^ 3 / 3 * 1 / 9) = XY (mean inequality) if and only if x ^ 3 = y ^ 3 / 3 = 1 / 9, the equal sign holds

(1) Given lgx = a, lgY = B, find LG √ X-LG (Y / 10), use a, B to represent (2) given 3x = 12Y = 8, find 1 / X - 1 / y

(1) The original formula = (1 / 2) lgx - (2lgy-2) = 1 / 2a-2y + 2 (2) from the title, we know that x = log is the logarithm of 12 with 3 as the base, and y = 2 can be substituted into the calculation