Question

$sqrt{a}+ sqrt{4}= sqrt{81}$
чему равно а=?
49 или 7?

Answer 1

√ a + √ 4 = √ 81
√ a = √ 81 - √ 4 = 9 - 2 = 7 
( √ a )² = 7²
a = 49 

Answer 2

$sqrt{a}+ sqrt{4}= sqrt{81} \ \ sqrt{a} = sqrt{81} - sqrt{4} \ \ sqrt{a} = 9 - 2 = 7 \ \ (sqrt{a})^2 = 7^2 \ \ a = 49$

Ответ: a = 49