Question

Which of the following is the complete factorization of 10x - 3 - 3x2? -(3x + 1)(x - 3) -(3x - 1)(x - 3) (3x - 1)(x + 3)

Answer 1

`=-\left(3x-1\right)\left(x-3\right)`

Explanation:

`10x-3-3x^2\\\mathrm{Factor\:out\:common\:term\:}-1\\=-\left(3x^2-10x+3\right)\\\mathrm{Factor}\:3x^2-10x+3:\quad \left(3x-1\right)\left(x-3\right)\\3x^2-10x+3\\\mathrm{Write\:in\:the\:standard\:form}\:ax^2+bx+c\\=3x^2-10x+3\\\mathrm{Break\:the\:expression\:into\:groups}\\=\left(3x^2-x\right)+\left(-9x+3\right)\\\mathrm{Factor\:out\:}x\mathrm{\:from\:}3x^2-x\mathrm{:\quad }x\left(3x-1\right)\\3x^2-x\\\mathrm{Apply\:exponent\:rule}:\quad \:a^(b+c)=a^ba^c\\x^2=xx\\=3xx-x`

`\mathrm{Factor\:out\:common\:term\:}x\\=x\left(3x-1\right)\\\mathrm{Factor\:out\:}-3\mathrm{\:from\:}-9x+3\mathrm{:\quad }-3\left(3x-1\right)\\-9x+3\\\mathrm{Rewrite\:}9\mathrm{\:as\:}3\cdot \:3\\=-3\cdot \:3x+3\\\mathrm{Factor\:out\:common\:term\:}-3\\=-3\left(3x-1\right)\\=x\left(3x-1\right)-3\left(3x-1\right)\\\mathrm{Factor\:out\:common\:term\:}3x-1\\=\left(3x-1\right)\left(x-3\right)\\=-\left(3x-1\right)\left(x-3\right)`