Question

please help me fast ​

Answer 1

Answer:

{A} 41

The calculations is as follows:

We know that :

$( {a + b)}^{2} = {a}^{2} + {b}^{2} + 2ab$

So, to obtain a^2 +b^2, we have to subtract 2ab from the total. Now,

${a}^{2} + {b}^{2} = {(a + b)}^{2} - 2ab$

Now, putting the values given, we get:

${a}^{2} + {b}^{2} = ( {9)}^{2} - 2(20)$

${a}^{2} + {b}^{2} = 81 - 40$

${a}^{2} + {b}^{2} = 41$

Hence, the answer is 41. Hope this helps! Please mark this as brainliest.

Answer 2

Answer:

$(a) \: \: \: \: \: \: \: \: \: \: {a}^{2} + {b}^{2} = ( {a + b)}^{2} \\ as \: \: \: \: \: a + b = 9 \\ so \: \: \: \: ({a + b)}^{2} = {9}^{2} = 81 \\ the \: answer \: is \: \: 81$

sorry for the (b)