hi everyone i need to hand in my assignment and i havnt answered few questions and i dont understand them they are the hard ones i tryed bout cudnt do them in order for me to pass i need to do this questions please help me .
1. The sum of the first n temrs of a certin arithmetic progression is given by Sn ( big s and little n under it ) = N2 ( n to the power of 2 ) + 3n
a) Find Expression for Sn-1 ( big s little n underit with - 1) and deduce an expression for Un ( big u with little n under it )
b) find the first term and the common difference
2. the lengths of the sides of a triangle are in geometric progression. the length of the shortest side is 6cm and the primeter of the triangle is 28 1/2 ( 28 and 0.5 ) find the lenth of the other sides.
3. in a geometric progression the sum to infinity 9 and the sum of the first two terms is 5. find the first 4 terms of the porogression given that they are positive .
thank you very much
1. The sum of the first n temrs of a certin arithmetic progression is given by Sn ( big s and little n under it ) = N2 ( n to the power of 2 ) + 3n
a) Find Expression for Sn-1 ( big s little n underit with - 1) and deduce an expression for Un ( big u with little n under it )
b) find the first term and the common difference
2. the lengths of the sides of a triangle are in geometric progression. the length of the shortest side is 6cm and the primeter of the triangle is 28 1/2 ( 28 and 0.5 ) find the lenth of the other sides.
3. in a geometric progression the sum to infinity 9 and the sum of the first two terms is 5. find the first 4 terms of the porogression given that they are positive .
thank you very much