What is the value of a if the gradient of PR is -2?
2 Answers
Jan 29, 2018
Explanation:
find the coordinates of P and Q
∙ let x = 0, in equation for y-intercept
∙ let y = 0, in equation for x-intercept
x=0→y2=1⇒y=2←y-intercept
y=0→x3=1⇒x=3←x-intercept
⇒P=(3,0) and Q=(0,2)
(a)
mQR=12 and R=(2a,y)
using the gradient formula
∙xm=y2−y1x2−x1
with Q=(0,2) and R=(2a,y)
⇒y−22a−0=y−22a=12
⇒2(y−2)=2a
⇒y−2=a⇒y=a+2
⇒R=(2a,a+2)
(b)
using the gradient formula with
P(3,0) and R(2a,a+2)
⇒a+22a−3=−2
⇒a+2=−4a+6
⇒5a=4⇒a=45
Jan 29, 2018
See below.
Explanation:
First the coordinates for
Now calling
for
and for
but