If (x-2) and (x+2) are factors of ax⁴+2x-3x²+bx-4.Find the value of a+b.
Plz give the ans and explanation .
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if (x + 2) is a factor of ax⁴ + 2x - 3x² + bx - 4
then x + 2 = 0 and x = - 2
ax⁴ + 2x - 3x² + bx - 4 = 0
substituting x = - 2 gives
16a - 4 - 12 + bx - 4 = 0
after simplifying
16a - 2b = 20
or
8a - b = 10
again,
if (x - 2) is a factor of ax⁴ + 2x - 3x² + bx - 4
then x - 2 = 0 and x = 2
ax⁴ + 2x - 3x² + bx - 4 = 0
substituting x = 2 gives
16a + 4 - 12 + bx - 4 = 0
which simplifies as
16a - 2b = 12
or
8a + b = 6
⇒ the equations are
8a - b = 10
8a + b = 6
from here we get
a=1
b= -2
a+b= 1+(-2) = -1
∴ for ax⁴ + 2x³ - 3x² + bx - 4 it'll be
by substituting x = - 2
16a - 16 - 12 - 2b - 4 = 0
and simplifying
8a - b = 16
again,
by substituting x = 2
16a + 16 - 12 + 2b - 4 = 0
after simplyfying
8a + b = 0
∴ we get
a = 1
b = - 8
a + b = - 7
then x + 2 = 0 and x = - 2
ax⁴ + 2x - 3x² + bx - 4 = 0
substituting x = - 2 gives
16a - 4 - 12 + bx - 4 = 0
after simplifying
16a - 2b = 20
or
8a - b = 10
again,
if (x - 2) is a factor of ax⁴ + 2x - 3x² + bx - 4
then x - 2 = 0 and x = 2
ax⁴ + 2x - 3x² + bx - 4 = 0
substituting x = 2 gives
16a + 4 - 12 + bx - 4 = 0
which simplifies as
16a - 2b = 12
or
8a + b = 6
⇒ the equations are
8a - b = 10
8a + b = 6
from here we get
a=1
b= -2
a+b= 1+(-2) = -1
∴ for ax⁴ + 2x³ - 3x² + bx - 4 it'll be
by substituting x = - 2
16a - 16 - 12 - 2b - 4 = 0
and simplifying
8a - b = 16
again,
by substituting x = 2
16a + 16 - 12 + 2b - 4 = 0
after simplyfying
8a + b = 0
∴ we get
a = 1
b = - 8
a + b = - 7
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