asked 197k views
2 votes
If (a+b)=12,ab=32 find(a²+b²) and (a-b)²

1 Answer

7 votes

Answer:

(a²+b²) = 80 and (a-b)² = 16

Explanation:

Let's first expand out (a-b)^2.

a^2 - 2ab + b^2

(a^2 + b^2) - 2*ab

The goal is to find what a^2 + b^2 is.

Now while we can use system of equations to find the separate values of a and b and then plug it in, there is a more efficient way to solve this problem. See below.

Let's square both sides of the equation (a+b) = 12

(a+b)^2 = 12^2 Now we can expand and simplify this equation

a^2 + b^2 + 2ab = 144

We know the value of ab because it is given so let's substitute that in.

a^2 + b^2 + 2*32 = 144

Now let's solve for a^2 + b^2 by taking 2*32 to the other side and simplifying.

a^2 + b^2 = 144 - 64 = 80

a^2 + b^2 = 80

Now to find the value of (a-b)^2

We expanded this out earlier and found that its a combination of a^2+b^2 and -2ab, both values which we have. So let's substitute in, simplify, and get our answer.

(a^2 + b^2) - 2*ab

80 - 2*32 = 80 - 64 = 16

Hope this helps :)

answered
User Gmadar
by
9.1k points

Related questions

Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.