Find the value of p if frac 1 4 p 3q 10 and 2p ... - WAEC Mathematics 2015 Question
Find the value of p if \(\frac{1}{4}\)p + 3q = 10 and 2p - q = 7
A
4
B
3
C
-3
D
-4
correct option: a
\(\frac{1}{4}\)p + 3p = 10...(1)
2p - \(\frac{1}{3}\)q = 7...(2)
Multiply equation (2) by 3 to clear fraction
3 x 2p - 3 x \(\frac{1}{3}\)q = 3 x 7
6p - q = 21
6p - 21 = q....(3)
substituting 6p - 21 for q in (1)
\(\frac{1}{4}\)p + 3(6p - 21) = 10...(4)
Multiply equation (4) by 4 to clear fraction
4 x \(\frac{1}{4}\)p + 4 x 3(6p - 21) = 4 x 10
p + 12(6p - 21) = 40
p + 72p - 252
73p = 292
p = \(\frac{292}{73}\)
= 4
2p - \(\frac{1}{3}\)q = 7...(2)
Multiply equation (2) by 3 to clear fraction
3 x 2p - 3 x \(\frac{1}{3}\)q = 3 x 7
6p - q = 21
6p - 21 = q....(3)
substituting 6p - 21 for q in (1)
\(\frac{1}{4}\)p + 3(6p - 21) = 10...(4)
Multiply equation (4) by 4 to clear fraction
4 x \(\frac{1}{4}\)p + 4 x 3(6p - 21) = 4 x 10
p + 12(6p - 21) = 40
p + 72p - 252
73p = 292
p = \(\frac{292}{73}\)
= 4
Please share this, thanks:
Add your answer
No responses