We know that equation of line through two points (x1,y1) and (x2,y2) is
y−y1=y2−y1x2−x1(x−x1)
So, equation of the line through the points (−1,1) and (2,−4) is
(y−1)=−4−12−(−1)(x−(−1))
⇒(y−1)=−52+1(x+1)
⇒(y−1)=−53(x+1)
⇒3(y−1)=−5(x+1)
⇒3y−3=−5x−5
⇒5x+3y+2=0
Hence, the required equation is 5x+3y+2=0