Question 5:
Solution:
Solve the equation:
(m + 2)(m – 4) = 7(m – 4).
(m + 2)(m – 4) = 7(m – 4)
m2– 4m + 2m – 8 = 7m – 28
m2– 9m + 20 = 0
(m – 5)(m – 4) = 0
m = 5 or m = 4
Question 6:
Solution:
−6y−2y=71−y(−6y−2)(1−y)=7y−6y+6y2−2+2y−7y=06y2−11y−2=0(6y+1)(y−2)=06y+1=0ory=2y=−16
Solve the equation:
−6y−2y=71−y
Solution:
−6y−2y=71−y(−6y−2)(1−y)=7y−6y+6y2−2+2y−7y=06y2−11y−2=0(6y+1)(y−2)=06y+1=0ory=2y=−16
Question 7:
Solution:
4m7=m(8m−9)4m=7m(8m−9)4m=56m2−63m56m2−63m−4m=056m2−67m=0m(56m−67)=0m=0or56m−67=0 m=6756
Solve the equation:
4m7=m(8m−9)
Solution:
Question 8:
Diagram above shows a rectangle ABCD.
(a) Express the area of ABCD in terms of n.
(b) Given the area of ABCD is 60 cm2, find the length of AB.
Solution:
(a)
Area of ABCD
= (n + 7) × n
= (n2+ 7n) cm2
(b)
Given the area of ABCD = 60
n2+ 7n = 60
n2+ 7n – 60 = 0
(n – 5) (n + 12) = 0
n = 5 or n = – 12 (not accepted)
When n = 5,
Length of AB = 5 + 7 = 12 cm