Sum the integers 13 to 500

125172

Step-by-step explanation:

13 + 14 +15 +16 +...+500

= ( 13 +  500 ) + ( ( 13 + 1 ) + ( 500 - 1 ) ) + ( ( 13 + 2 ) + ( 500 - 2 ) )+

= (13 + 500) + (14 + 499) + ( 15 + 498) +

= 513 + 513 + 513 +

= 513 * n

to calculate the value of n  

(500 - 13 )=  487 +1  =488

thus n = 488 /2 = 244

so the answer is  513 * 244 = 125172

sum up :

if u see the question , Sum the integers a to b

the answer is (a+b)×(a-b+1)÷2

the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

step-by-step explanation: