$\sum\limits_{k=1}^7\,\big(2x_k-3\big)^2=\sum\limits_{k=1}^7\,\big(4x_k^2-12x_k+9\big)=\\\\\\=\sum\limits_{k=1}^7\,4x_k^2-\sum\limits_{k=1}^7\,\big12x_k+\sum\limits_{k=1}^7\,9=4\sum\limits_{k=1}^7\,x_k^2-12\sum\limits_{k=1}^7\,x_k+\sum\limits_{k=1}^7\,9=\\\\\\=4\cdot672-12\cdot56+7\cdot9=2688-672+63=\boxed{2079}$

5 0

2 years ago

(8.75-2.16)÷7.1+(4.5+1.3)÷4.3

kirill [66]

Answer:

2.27700622339

Step-by-step explanation:

Calculated your welcome

7 0

2 years ago

Read 2 more answers

Plz help me well mark brainliest if correct

Firlakuza [10]

Answer:

C.11

Step-by-step explanation:

yellow fur and green eyes =19 students

brown fur and brown eyes= 8 students

subtract them

19-8=11 students

3 0

2 years ago

Round the number 15.39624 to 2 decimal places​

Round the number 15.39624 to 2 decimal places