Question

2
20. If and –3 are the zeros of the quadratic polynomial ax? +7x+b then
3
find the values of a and b.
[CBSE 2011]​

Answer 1

Given roots are: x = 2/3 and x = -3 and quadratic equation ax2 + 7x + b = 0

Since x = 2/3 and x = -3 are roots of the above quadratic equation

Hence, will satisfy the given equation.

Step 1: At x = 2/3 a(2/3)2 + 7(2/3) + b=0 4/9 a + 14/3 + b = 0 4a + 42 + 9b = 0 equation (1)

Step 2: At x = –3 a(-3)2 + 7(-3)+b=0 9a – 21 + b = 0. .equation (2)

Step 3: Solving equation (1) and equation (2), we get a = 3, b = –6

Answer 2

Step-by-step explanation:

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