What are the means of the following proportion? \( 3 / 15=12 / 60 \)

Evaluate the expression without using a calculatc \( \log _{2} 1 \) \( \log _{2} 1= \) (Type an integer or a simplified fraction.)

(4) Na PC cujo enésimo termo é a \( =-2 \cdot 3^{\circ} \). os quatro primeiros termos são \( -6,-18,-54,-162 \). Calcule o \( 20^{\circ} \) termo.

\( 21 mm = \square cm \)

6n−28.8<−24+5n Step 1 of 2 : Solve the inequality and express your answer in interval notation. Use decimal form for numerical values.

(2) Hallar los puntos de interseccién de areuferenclas a) \( x^{2}+y^{2}-4 x-6 y+13=0 \) \( x^{2}+y^{2}-8 x-10 y+17=0 \) b) \( x^{2}+y^{2}+6 x-12 y+20=0 \) \( x^{2}+y^{2}+9 x-9 y+5=0 \)