Question

5(3x2 + ?x - 2) = 15x2 - 20x - 10

Answer 1

Let's start:

`5(3x^2+?x-2)=15x^2-20x-10`

To find the coefficient missing here, you simply have to use ''multiply and divide property of equality'' and ''add and subtract property of equality'':

`\begin{gathered} 15x^2+5?x-10=15x^2-20x-10 \\ \text{the same terms on the both sides, so you can eliminate them , then:} \\ 5\text{?x}=-20x \\ ?=(-20x)/(5x) \\ ?=-4 \end{gathered}`