Question

If f(x)=(a - 2)x+(-3)x2 + 5x +7 is a linear polynomial then (a+b) ab is equal to :
O 30
O 5
O 6
O
Data is insufficient​

Answer 1

SOLUTION

TO CHOOSE THE CORRECT OPTION

$\sf{If \: \: f(x) = (a - 2) {x}^{3} + (b - 3) {x}^{2} + 5x + 7}$

is a linear polynomial then (a+b)ab is equal to is a linear polynomial then (a+b)ab is equal to

• 30

• 5

• 6

EVALUATION

Here the given polynomial is

$\sf{ f(x) = (a - 2) {x}^{3} + (b - 3) {x}^{2} + 5x + 7}$

Since f(x) is a linear polynomial

So

Coefficient of x³ = 0

Coefficient of x² = 0

Now Coefficient of x³ = 0 gives

a - 2 = 0

⇒ a = 2

Again Coefficient of x² = 0 gives

b - 3 = 0

⇒ b = 3

∴ (a + b) ab

= ( 2 + 3 ) × 2 × 3

= 5 × 2 × 3

= 30

FINAL ANSWER

Hence the correct option is 30

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