Solve the equation algebraically for all values of x. 8x^3 + 4x^2 - 18x - 9 = 0
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Originally Posted by MATNTRNG Solve the equation algebraically for all values of x. 8x^3 + 4x^2 - 18x - 9 = 0 Notice that this is $\displaystyle (2x)^3+(2x)^2-9(2x)-9=0$ $\displaystyle 2x=-1$ is a solution, so (2x+1) is a factor. $\displaystyle (2x+1)\left(4x^2+bx-9)$ are the factors, so you only need find "b" and factor the quadratic.
Originally Posted by MATNTRNG Solve the equation algebraically for all values of x. 8x^3 + 4x^2 - 18x - 9 = 0 Hi MATNTRNG, First, factor by grouping. $\displaystyle 8x^3+4x^2-18x-9=0$ $\displaystyle (8x^3+4x^2)-(18x+9)=0$ $\displaystyle 4x^2(2x+1)-9(2x+1)=0$ $\displaystyle (4x^2-9)(2x+1)=0$ I'll bet you can take it from here. Right?
Originally Posted by MATNTRNG Solve the equation algebraically for all values of x. 8x^3 + 4x^2 - 18x - 9 = 0 $\displaystyle 8x^3+4x^2-18x-9=4x^2(2x+1)-9(2x+1)$
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