if 2 is a zero of both the polynomial 3x²+ax-4 and 2x³+bx+x-2,then the value of a+2b is.
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Fill value 2 in place of x
3x²+ax-4 = 0
3(2)²+a(2)-4 = 0
3(4)+2a-4 = 0
12 - 4 +2a = 0
8 + 2a = 0
2a = -8
a = -8/2
a = -4
2x³+bx+x-2 = 0
2(2)³+b(2)+2-2 = 0
2(8) +2b = 0
16 + 2b = 0
2b = -16
b = -16/2
b = -8
so value of
a + 2b
= -4 + 2(-8)
= -4 - 16
= -20
3x²+ax-4 = 0
3(2)²+a(2)-4 = 0
3(4)+2a-4 = 0
12 - 4 +2a = 0
8 + 2a = 0
2a = -8
a = -8/2
a = -4
2x³+bx+x-2 = 0
2(2)³+b(2)+2-2 = 0
2(8) +2b = 0
16 + 2b = 0
2b = -16
b = -16/2
b = -8
so value of
a + 2b
= -4 + 2(-8)
= -4 - 16
= -20
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