# Where does the parabola #x^2-3x=40# have roots?

##### 1 Answer

May 11, 2017

#### Explanation:

#"rearrange and equate to zero"#

#rArrx^2-3x-40=0#

#"splitting the middle term gives"#

#x^2-8x+5x-40=0#

#"factorising"#

#x(x-8)+5(x-8)=0#

#"taking out the factor " (x-8)#

#rArr(x-8)(x+5)=0larr" equate each factor to zero"#

#x-8=0rArrx=8#

#x+5=0rArrx=-5#

#rArrx=-5" and " x=8" are the roots"#

graph{x^2-3x-40 [-10, 10, -5, 5]}