Question

check whether x = -4 is a solution of the equation x^4 + 5x^3 + 6x -7 = 0

Answer 1

Dear Student,

$$\begin{gathered} Letf\left(x\right)=x^4+5x^3+6x-7=0 \\ forx=-4tobeasolutionoff\left(x\right),f\left(-4\right)mustbeequalto0. \\ f\left(-4\right)={\left(-4\right)}^4+5{\left(-4\right)}^3+6\left(-4\right)-7 \\ f\left(-4\right)=256-5\times 64-24-7 \\ f\left(-4\right)=256-320-24-7 \\ f\left(-4\right)=-95whichisnotequaltozero. \\ Hence,x=-4isnotasolutionof{x}^4+5x^3+6x-7=0 \end{gathered}$$

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