Question

如图,已知一次函数y=kx+b的图像经过A(-2,-1),B(1,3)两点求△AOB的面积.

Answer 1

根据题意得方程组：

{-1=-2K+b

{3=K+b

解得：K=4/3,b=5/3,

∴Y=4/3X+5/3,

令X=0,Y=5/3,∴D(0,5/3),OD=5/3,

SΔOAB=SΔODA+SΕODB

=1/2×5/3×2+1/2×5/3×1

=5/3+5/6

=5/2.