How do you find the x and y intercepts for #y= -3x-9#?

2 Answers

Answer:

the x-intercept #=(-3, 0)#
the y-intercept #=(0, -9)#

Explanation:

To solve for the x-intercept, set #y=0# then solve for x

#y=-3x-9#
#0=-3x-9#
#3x=-9#

#x=-3# when #y=0#

therefore #(-3, 0)# is the x-intercept

To solve for the y-intercept, set #x=0# then solve for y

#y=-3x-9#
#y=-3(0)-9#
#y=-9# when #x=0#

therefore #(0, -9)# is the y-intercept

God bless....I hope the explanation is useful.

Apr 23, 2016

Answer:

#y_("intercept")=-9->(x,y)->(0,-9)#

#x_("intercept")=-3->(x,y)->(-3,0)#

Explanation:

Reading directly from the equation:

#color(blue)(y_("intercept")=-9)#

The graph crosses the x-axis when y=0

Substituting #y=0# gives#

#0=-3x-9#

Add #color(blue)(9)# to both sides

#color(brown)(0color(blue)(+9)=-3x-9color(blue)(+9))#

#9=-3x+0#

Divide both sides by #color(blue)(3)#

#color(brown)(9/(color(blue)(3))=(-3)/(color(blue)(3))xx x)#

But #9/3=3" and "(-3)/3=-1#

#=>3=(-1)xx x#

#-x=3#

Multiply both sides by (-1)

#x=-3#

#color(blue)(x_("intercept")=-3)#
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Tony B