Monday

March 2, 2015

March 2, 2015

Posted by **Bethany** on Wednesday, July 2, 2014 at 11:43pm.

I figured out the answer by adding them with a calculator but i was wondering if there was an algebraic way of solving this?

- Math -
**Steve**, Thursday, July 3, 2014 at 12:15amSince you are adding 20 to each number, just add 20*21 to the total.

Or, thinking of the values as an arithmetic progression, recall that the sum of n terms is

Sn = n/2 (T1+Tn)

With a=40,d=1,

S21 = 21/2 (40+60) = 1050

With a=60,d=1,

S21 = 21/2 (60+80) = 1470

Note that 1470 = 1050 + 21*20

- Math -
**Bethany**, Thursday, July 3, 2014 at 12:26amOk, thank you!

**Answer this Question**

**Related Questions**

Math - The sum of the integers from 40 to 60, inclusive, is 1050. what is the ...

Math - The sum of the integers from 40 to 60, inclusive, is 1050. what is the ...

algebra - The sum of the first n counting numbers 1 + 2 + 3 + 4 + 5 ... + n is ...

Geometry - I am having a little trouble understanding this... could someone help...

Math ( Number Theory ) - How many numbers from 1 to 1000 inclusive can be ...

SAT math - Set M consists of the consecutive integers from -15 to y, inclusive. ...

SAT prep help - Set M consists of the consecutive integers from -15 to y, ...

Math (algebra) - Let x,y be complex numbers satisfying x+y=a xy=b, where a and b...

math - list the integers between -5 and 2, inclusive.

child care - hello i need some help with those questions (the legal requirements...