Answer:
(x+3)(x+7)
Step-by-step explanation:
Easy, all you do is look at the numbers, 3*7 = 21, and no other choice has digits that multuply to 21
The factorized expression is (a) (x + 3)(x + 7)
The expression is given as:
[tex]x^2 + 10x + 21[/tex]
Expand the expression i.e. express 10x as 7x _ 3x
[tex]x^2 + 7x + 3x + 21[/tex]
Factorize
[tex]x(x + 7) + 3(x + 7)[/tex]
Factor out x + 7
[tex](x + 3)(x + 7)[/tex]
Hence, the factorized expression is (a) (x + 3)(x + 7)
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