Asked by Anonymous
The sum of two numbers is 20. The difference of their squares is 120. What are the numbers?
Answers
Answered by
Damon
a + b = 20
a^2-b^2 = 120
(a+b)(a-b) = 120
20(a-b) = 120
a-b = 6
so
a+b = 20
a-b = 6
I bet you can solve that
a^2-b^2 = 120
(a+b)(a-b) = 120
20(a-b) = 120
a-b = 6
so
a+b = 20
a-b = 6
I bet you can solve that
Answered by
josphat
y=7 and x=9
Answered by
Gwyneth Skylar
X+Y=20 OR X=20-Y
X^2-Y^2=120
(20-Y)^2-Y^2=120
400-40Y+Y^2=120
-40Y=120-400
-40Y=-280
Y=-280/-40
Y=7 ans.
X+7=20
X=20-7
X=13 ans.
Proof:
13^2-7^2=120
169-49=120
120=120
X^2-Y^2=120
(20-Y)^2-Y^2=120
400-40Y+Y^2=120
-40Y=120-400
-40Y=-280
Y=-280/-40
Y=7 ans.
X+7=20
X=20-7
X=13 ans.
Proof:
13^2-7^2=120
169-49=120
120=120