Question

if x=4 is the solution of the equation 3x²+kx-2=0 find the value of k ​

Answer 1

Answer:

$given \: that x = 4 \\ p(x) = 3 {x}^{2} + kx - 2 \\ keep \: x \: value \: in \: p{x} \\ 3( {4})^{2} + k4 - 2 = 0 \\ 3 \times 16 + k4 - 2 = 0 \\ k4 - 2 + 48 = 0 \\ k4 = 0 - 46 \\ k = - 46 \div 4 \\ k = - 11.5$

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Answer 2

$3\cdot4^2+k\cdot 4-2=0\\48+4k-2=0\\4k=-46\\k=-\dfrac{23}{2}$