Using Gauss's method
Total number of terms = [15-(-129)]/4+1=36+1=37
Add
S=15+11+7+....-125-129
S=-129-125-...+7+11+15
--------------------------------
2S=-114-114-114...(37 times)
=>
sum=S=(1/2)*(-114)*37=-2109
Using AP, T(n)=15+11+7+....-129
T(n)=19-4n => T(1)=15, T(37)=-129
S(n)=(1/2)(37)(T(1)+T(37)=(1/2)37(15-129)=2109
4.a)2x+10 >27
4.b) 27-10= 17
17/2=8.5
3.a) 40-2x>7
3.b) 7-40=-33
-33/-2=16.5
So 16 students in her class
Answer:
7.5x6.5=48.75
Step-by-step explanation:
Answer:
1 lakh means 1,00,000 which is equal to one hundred thousand
Therefore 1,00,000=(100×10000)
Hence one hundred thousand make a lakh