Question

The polynomial 3x^2+bx-4 has x-a as a factor. where a is not equal to 0 express b in terms of a

Answer 1

hint : if (x-a) is a factor of f(x), then f(a) = 0

Answer 2

@ganeshie8 thanks! but i srsly dont know how to answer this tho. i need help T.T

Answer 3

since x-a is a factor of given polynomial(say f(x)), f(a) must equal 0

Answer 4

plugin x = a and set it equal to 0

Answer 5

3x^2+bx-4

plugin x = a, what do u get ?

Answer 6

3a^2 + ba - 4 = 0. am i right?

Answer 7

Excellent ! next just isolate `b`

Answer 8

so... ba = -3a^2 + 4 and then, b = -3a^2 + 4/a. is the answer b = -3a^2 + 4?

Answer 9

yes

3a^2 + ba - 4 = 0

ba = -3a^2 + 4

b = (-3a^2+4)/a

Answer 10

-3a^2 + 4/a is the answer not -3a^2 + 4?

Answer 11

cant i cancel a in the denominator by the a in 3a^2?

Answer 12

thats a good observation ! yes you can

Answer 13

b = (-3a^2+4)/a
= -3a^2/a + 4/a
= -3a + 4/a

Answer 14

thank you so much!!!

Answer 15

np :)