Posted by Dhanalakshmi on Wednesday, March 16, 2011 at 8:58am.
In Geometric progression the sum of first of three terms is 28 and the product is 512 find those numbers

math  bobpursley, Wednesday, March 16, 2011 at 9:18am
a+ar+ar^2=28
a^3 * r^3=512
one the second equation, take the cube root of each side.
ar=cubrt(512)=8
a+8+ar^2=28
a(1+r^2)=20
but a= 8/r
8(1+r^2)=20r
8r^220 r+8=0
r=(20)+sqrt(400256) /16
r=20+ sqrt(144) /16 = (20+12)/16=2 or 1/2
then a= 4 or 16
check a=4, r=2
4 + 8 + 16=28
a^3 r^3=64*8=512 checks, a=4, r=2
check a=8, r=1/2
8 +4 + 2 does not check.
Answer This Question
Related Questions
 math  There are two positive numbers that can be inserted between 3 and 9 such ...
 Math (Geometric Progression)  5 distinct positive reals form an arithmetic ...
 mathematics :geometric progression  The first three terms of a geometric ...
 math C2 sequences and series  The eight,fourth and second terms of an ...
 Math  5 distinct positive reals form an arithmetic progression. The 1st, 2nd ...
 plz sequence sir steve reiny bob damon i need u  The three real,distint and non...
 math  1)Find the sum of the first eight terms of the Geometric progression 256,...
 Algebra 2  In an infinite geometric progression with positive terms and with a ...
 math  The sum of the 3 terms in arithmetic sequence is 39.if these numbers is ...
 Math  Three numbers form a geometric progression. If 4 is subtracted from the ...
More Related Questions