# Pre-CalcPlease check

posted by
**Bethany** on
.

Please check:

1.Write in expanded form: this is a sigma notation-

4 on top

signma in middle

k=1 on bottom

to right of sigma is (k-1)(k-2)

I solved:

k=1 (1-1)(1-2)=0(-1)=0

K=2 (2-1)(2-2) = 1(0)=0

k=3(3-1)(3-2)=2(1)=2

k=4 (4-1)(4-)=3(2)=6

answer: 0+0+2+6

2. Write 4+9+16+25+36+49+64 in sigma notation

answer: 8 on top

sigma in middle

i=2 on bottom

x^2 to right of sigma

3. Write 88+79+70+61+...+-83 in sigma notation

my work:there is (-9) common difference

97-9(1)=88

97-9(2)=79

97-9(3)=70

97-9(4)=61

97-9(20)= -83

20 on top

sigma in middle

answer:i=1 on bottom to right of sigma is 97-9n