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Find a:

(x+3)(x+a)(x+7)=x³+15x²+71x+105

Sagot :

Answer:

a = 5

Step-by-step explanation:

(x+3)(x+a)(x+7)=x³+15x²+71x+105

(x+3)(x+a)(x+7) = (x²+10x+21)(x+a) = x³ + (10+a)x² + (21+10a)x + 21a

21a = 105

a = 5

check: 21 + 10a = 71   ... 71x

            10 + q = 15  .... 15x²