Question

If (x+a) is a factor of $2x^{2}+2ax+5x+10$,find a.

Answer 1

SOLUTION :  

Let f(x) = 2x² + 2ax + 5x +10

Since, x + a is a factor of f(x).

Then,  x + a = 0

x = -a

Therefore, f(-a) = 0

f(x) = 2x² + 2ax + 5x +10

2(-a)² + 2a(-a) + 5(-a) +10 = 0

2a² - 2a² -5a +10 = 0

-5a + 10 = 0

-5a = -10

a= 10/5

a = 2

Hence, the value of a is 2 .

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Answer 2

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