In an arithmetic sequence, the sum of the first four sentences is 15 and the sum of the next five sentences is 30. Calculate the eleventh sentence of this sequence

Step-by-step explanation:

Formula 1

Given an arithmetic sequence, we can calculate the sum of its first n terms, which we write Sn, using the formula:

Sn=n2(u1+un)

Where u1 is the first term of the sequence and un is the nth term.

So, for example, S10 refers to the sum of the first 10 terms, S250 refers to the sum of the first 250 terms, ... .

3< x< 5

step-by-step explanation:

|x - 4| < 1

there are two solutions, one positive and one negative.   remember to flip the inequality when taking the negative solution

x-4 < 1       x-4 > -1

add 4 to each side

x-4+4 < 1+4       x-4+4 > -1+4

x< 5                 x> 3

3< x< 5

d) by the cross product property, ab^2 = bc multiplied by ad

step-by-step explanation:

we are given

in the given triangle abc

angle a is 90° and segment ad is perpendicular to segment bc

we can see that

triangle(abc) and triangle(abd) are similar because they have common side and same angle (90 degree)

so, triangles(abc) and abd are similar

since, they are similar

so, the ratio of their sides must be equal

we get

now, we can cross multiply

and we get

so, this could be step to prove it