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| 1. |
To accelerate a 2.0 kg mass by 4 m/s? we need a force |
| Answer» GIVEN: a n =5−6nFind some of the TERMS of AP:Put n=1, we get a 1 =−1= first termPut n=2, we get a 2 =−7= second termCommon difference=d=a 2 −a 1 =−7−(−1)=−6Sum of first n terms:S n =n/2[2a+(n−1)d]=n/2[−2+(n−1)(−6)]=n(2−3n)Sum of first 20 terms:S 20 =20/2[2(−1)+(20−1)(−6)]=10[−2−114]=−1160Sum of its first 20 terms of AP is −1160. | |