SOLUTION: If a^2-b^2=70 and a-b=7, what is the value of a?

Algebra ->  Customizable Word Problem Solvers  -> Geometry -> SOLUTION: If a^2-b^2=70 and a-b=7, what is the value of a?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 388996: If a^2-b^2=70 and a-b=7, what is the value of a?
Found 4 solutions by richard1234, haileytucki, mananth, josmiceli:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Since a%5E2+-+b%5E2+=+%28a-b%29%28a%2Bb%29+=+70 we can replace a-b with 7 and get a%2Bb+=+10

We have the system of equations a%2Bb+=+10 and a-b+=+7. Adding them, we obtain 2a+=+17 --> a = 17/2.

Answer by haileytucki(390) About Me  (Show Source):
You can put this solution on YOUR website!
a%5E%282%29-b%5E%282%29=70_a-b=7
This system of equations cannot be solved because there are more unique variables (4) than there are equations (2).
The system cannot be solved.

Can you repost this exactly how it appears? Or is there a slight error within the numbers?

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
If a^2-b^2=70 and a-b=7, what is the value of a?
...
a^2-b^2= 70
(a+b)(a-b)=70
a-b=7
substitute the value of a-b
(a+b)*7=70
/7
a+b=10
a-b=7
add them up
2a=17
/2
a= 17/2
b=1.5
...
Check
a^2-b^2=70
(17/2)^2-(1.5)^2 =70
...
m.ananth@hotmail.ca

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
given:
a%5E2+-+b%5E2+=+70
a+-+b+=+7
------------
b+=+a+-+7
a%5E2+-+%28a+-+7%29%5E2+=+70
a%5E2+-+%28a%5E2+-+14a+%2B+49%29+=+70
a%5E2+-+a%5E2+%2B+14a+-+49+=+70
14a+=+70+%2B+49
14a+=+119
a+=+8.5
check:
b+=+a+-+7
b+=+1.5
a%5E2+-+b%5E2+=+70
8.5%5E2+-+1.5%5E2+=+70
72.25+-+2.25+=+70
70+=+70
OK