toán 8

T

thienbinhgirl

a, Xét $2x^3+x^2+ax+b$ với $2x^2+5x-3$= $(2x-1)(x+3)$ \Rightarrow $2x^3+x^2+ax+b$ = $(2x-1)(x+3)$ . $Q_(x)$
Lần lượt thay
$x=-3$ \Rightarrow -3a + b = 45
$x=\frac{1}{2}$ \Rightarrow $\frac{1}{2}a + b = \frac{-1}{2}$

\Leftrightarrow $a=-13$ ; $b=6$
 
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