Express 9-y^2 as the product of two binomial factors.

3^2-y^2

then apply formula (a-b)(a+b)=a^2-b^2

so,,
(3-y)(3+y)

Recognize the difference of 2 perfect squares
remember that
a²-b²=(a-b)(a+b)
so
9=3²
y²=y²

9-y²=
3²-y²=
(3-y)(3+y)

Answer: d. 39 cmin the diagram, the approximate length of the minor arc de is 39 centimetres.step-by-step explanation: the formula for the length of an arc in a circle is as displayed below.let the length of the minor arc de = xx = 2( pi )r × angle of sector / 360°from this, we will substitute the values given from the problem into the formula to obtain the length of the minor arc de.x = 2( pi )r × angle of sector / 360°r = radius = 25cmpi as an approximate value = 3.14angle of sector = 120°x = 2( 3.14 )( 25 ) × 120° / 360°x = 157 × 1 / 4x = 39.25x = 39 ( rounded to the nearest whole number as an approximate value )