Can anybody help me with this one?

  12 cm

Step-by-step explanation:

The rule regarding secants and/or tangents is that the product of distances from their common point to the two intersection points with the circle is the same.

For the tangent the "two" intersection points with the circle are the same point, so ...

  product of tangent lengths = product of secant lengths

  (8 cm)(8 cm) = (4 cm)(4 cm +x)

Dividing by 4 cm gives ...

  16 cm = 4 cm + x

  12 cm = x

no, the equation would be invalid since they are both not equal.

step-by-step explanation:

here you got

4y-6+4y 2-9

first, you would simplify the equation on the form.

4y-6+4y 2-9

then, move all the terms that contains a y to the left and all the other terms to the right.

+4y-4y+-9-6

finally, you will simplify the left and the right side of the equation.

y=-3