Question

N 2.x 15x -4 = -3x2 to the nearest tenth.

Answer 1

x = 15.3 or -0.3

Here, we want to get the value of x from the given equation

Let us bring like terms together, we have;

`\begin{gathered} -2x^2-15x-4=-3x^2 \\ -2x^2+3x^2\text{ -15x - 4 = 0} \\ \\ x^2\text{ - 15x - 4 = 0} \end{gathered}`

We now proceed to use the quadratic formula to solve this quadaratic equation. The formula is;

`x\text{ = }\frac{-b\text{ }\pm\text{ }\sqrt[]{b^2\text{ - 4ac}}}{2a}`

In the case of this question, a = 1 , b = -15 and c = -4

Substituting these values in the quadratic formula, we have;

`\begin{gathered} x\text{ = }\frac{-(-15)\text{ }\pm\text{ }\sqrt[]{(-15)^2\text{ - 4(1)(-4)}}}{2(1)} \\ \\ x\text{ = }\frac{15\text{ }\pm\text{ }\sqrt[]{225\text{ + 16}}}{2} \\ \\ x\text{ = }\frac{15\text{ }\pm\text{ }\sqrt[]{241}}{2} \\ \\ x\text{ = }\frac{15\text{ }\pm\text{ 15.52}}{2} \\ \\ x\text{ = }\frac{15\text{ + 15.52}}{2}\text{ or }(15-15.52)/(2) \\ \\ x\text{ = }15.26\text{ or -0.26} \end{gathered}`

To the nearest tenth (one decimal place) x = 15.3 or -0.3