How do you solve 3x^2 -12x = 93x2−12x=9 using the quadratic formula?
1 Answer
Apr 24, 2017
Explanation:
"rearrange terms and equate to zero"rearrange terms and equate to zero
rArr3x^2-12x-9=0⇒3x2−12x−9=0
"divide all terms by 3"divide all terms by 3
rArrx^2-4x-3=0⇒x2−4x−3=0
"compare to standard form " ax^2+bx+c=0compare to standard form ax2+bx+c=0
"here " a=1,b=-4" and " c=-3here a=1,b=−4 and c=−3
"using the " color(blue)"quadratic formula"using the quadratic formula
color(red)(bar(ul(|color(white)(2/2)color(black)(x=(-b+-sqrt((b^2-4ac)))/(2a))color(white)(2/2)|)))
rArrx=(-(-4)+-sqrt((-4)^2-(4xx1xx-3)))/(2xx1)
color(white)(rArrx)=(4+-sqrt(16+12))/2=(4+-sqrt28)/2
color(white)(rArrx)=2+-1/2sqrt28
color(white)(rArrx)=2+-1/2sqrt(4xx7)
color(white)(rArrx)=2+-sqrt7