Welcome to Westonci.ca, where you can find answers to all your questions from a community of experienced professionals. Explore our Q&A platform to find in-depth answers from a wide range of experts in different fields. Connect with a community of professionals ready to help you find accurate solutions to your questions quickly and efficiently.

If [tex][tex]$x + y = 5$[/tex][/tex] and [tex][tex]$xy = 10$[/tex][/tex], then the value of [tex][tex]$x^2 + y^2$[/tex][/tex] is:

a) 5
b) 10
c) 15


Sagot :

Certainly! Let's find the value of [tex]\( x^2 + y^2 \)[/tex] given the equations [tex]\( x + y = 5 \)[/tex] and [tex]\( xy = 10 \)[/tex].

We start with the given equation:
[tex]\[ x + y = 5 \][/tex]

First, let's square both sides of the equation:
[tex]\[ (x + y)^2 = 5^2 \][/tex]
[tex]\[ x^2 + 2xy + y^2 = 25 \][/tex]

We also know:
[tex]\[ xy = 10 \][/tex]

Now, we substitute [tex]\( 2xy \)[/tex] into the squared equation:
[tex]\[ x^2 + 2xy + y^2 = 25 \][/tex]
[tex]\[ 2xy = 2 \times 10 \][/tex]
[tex]\[ 2xy = 20 \][/tex]

So,
[tex]\[ x^2 + y^2 + 20 = 25 \][/tex]

Next, we subtract 20 from both sides to isolate [tex]\( x^2 + y^2 \)[/tex]:
[tex]\[ x^2 + y^2 = 25 - 20 \][/tex]
[tex]\[ x^2 + y^2 = 5 \][/tex]

So, the value of [tex]\( x^2 + y^2 \)[/tex] is:
[tex]\[ \boxed{5} \][/tex]