Question

Find the missing terms in the equation so that it is true. (3x + ?)^2=9x^2 + ?? +49y^2

Answer 1

see explanation

Explanation:

Note that 9x² and 49y² are perfect squares.

9x² = (3x)² → 3x is the first term

49y² = (7y)² → 7y is the second term

Hence

(3x + 7y)² = 9x² + 42xy + 49y²