How do you solve using the completing the square method 2x^2 - 7x - 15 = 0?
1 Answer
Mar 30, 2018
Explanation:
"to use the method of "color(blue)"completing the square"
• " the coefficient of the "x^2" term must be 1"
rArr2(x^2-7/2x-15/2)=0
• " add/subtract "(1/2"coefficient of the x-term")^2" to"
x^2-7/2x
2(x^2+2(-7/4)xcolor(red)(+49/16)color(red)(-49/16)-15/2)=0
rArr2(x-7/4)^2+2(-49/16-15/2)=0
rArr2(x-7/4)^2-169/8=0
rArr2(x-7/4)^2=169/8
rArr(x-7/4)^2=169/16
color(blue)"take the square root of both sides"
rArrx-7/4=+-sqrt(169/16)larrcolor(blue)"note plus or minus"
rArrx=7/4+-13/4
rArrx=7/4-13/4=-3/2" or "x=7/4+13/4=5
