A+A+d+A+2d+a+3d=16
4A+6d=16
2A+3d=8
(A+3d)^2=A^2+48
second equation...
A^2+6dA+9d^2=a^2+48
3d(2A+3d)=48
3d*8=48
d=2
then 2A+6=8
A=1
1,3,5,7
The sum of four numbers in arithmetic progression is 16. The square of the last number is the square of the first number plus 48. What are the four numbers?
1 answer