 Hello and welcome to the session. Let us understand the following problem today. Find the sum given below. We have minus 5 plus minus 8 plus minus 11 plus so on till minus 230. Now let us write the solution. Given AP is minus 5 plus minus 8 plus minus 11 so on till minus 230. Now here A is equal to minus 5, D is equal to common difference so minus 8 minus of minus 5 which is equal to minus 8 plus 5 which is equal to minus 3 and A n is equal to the nth term that is minus 230. Now we know that A n is equal to A plus n minus 1 D. Now here A n is equal to minus 230 which is equal to A is minus 5 plus n is unknown and D is minus 3. Now solving this for n it implies minus 230 is equal to minus 5 minus 3n plus 3 which implies 3n is equal to minus 5 plus 3 plus 230 which implies 3n is equal to minus 2 plus 230 which implies 3n is equal to 228 which implies n is equal to 76. Now we have got the value of n so using this we can find some therefore s is equal to n by 2 multiplied by A plus A n. So which is equal to 76 by 2 A is minus 5 plus A n which is minus 230. Now solving this we get this gets cuts so we get here 38 so it is equal to 38 multiplied by minus 5 minus 230 which is equal to 38 multiplied by minus 235 which is equal to minus 8 9 3 0 therefore the required sum is minus 8 9 3 0. I hope you understood the problem by and have a nice day.