Question

SOLVE THE FOLLOWING PAIR BY SUBSTITUTION AND CROSS MULTIPLICATION
a) 8x+5y,3x+2y=4​

Answer 1

Answer:

hope it helps...

Answer 2

Answer:

x = -2 and y = 5

Step-by-step explanation:

Given Equations are,

8x + 5y = 9

8x + 5y - 9 = 0 ....................(1)

3x + 2y = 4

3x + 2y - 4 = 0 .......................(2)

here,

a_1=8\:,\:b_1=5\:,\:c_1=-9\:,\:a_2=3\:,\:b_2=2\:and\:c_2=-4

since, \frac{a_1}{a_2}\neq\frac{a_2}{b_2}

There exist unique solution,

By cross multiplication method we get,

\frac{x}{5\times(-4)-2\times(-9)}=\frac{y}{-9\times3-(-4)\times8}=\frac{1}{8\times2-3\times5}

First Consider,

\frac{x}{5\times(-4)-2\times(-9)}=\frac{1}{8\times2-3\times5}

\frac{x}{-2}=\frac{1}{1}

x=-2

Secondly consider,

\frac{y}{-9\times3-(-4)\times8}=\frac{1}{8\times2-3\times5}

\frac{y}{5}=\frac{1}{1}

y=5

Therefore, x = -2 and y = 5