Question

0.3x+0.4y =2.5,0.5x-0.3y =0.3 by cross multiply method​

Answer 1

Given : The equations 0.3x + 0.4y = 2.5 and 0.5x - 0.3y = 0.3

To find: Value of c and y by cross multiply method​.

Solution:

• Now we have given the equations as:

                  0.3x + 0.4y = 2.5 and 0.5x - 0.3y = 0.3

• We can rewrite the equations as:

                   0.3x + 0.4y - 2.5 = 0 and  0.5x - 0.3y - 0.3 = 0

• Now it is in the form:

                   a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 ............…(i)

• Now comparing the given equations with standard one, we get:

                   a1 = 0.3, b1 = 0.4, c1 = -2.5

                  a2 = 0.5, b2 = -0.3, c2 = -0.3

• Now for cross multiplication method, we have:

                  x / b1c2-b2c1 = y / c1a2-c2a1 = 1 / a1b2 - a2b1

• Applying cross multiplication method , we get:

                  x / (0.4)(-0.3) - (-0.3)(-2.5) = y / (-2.5)(0.5) - (-0.3)(0.3) = 1 / (0.3)(-0.3) - (0.5)(0.4)

                  x / -0.87 = y / -1.16 = 1 / -0.29

                  x / -0.87 = 1 / -0.29

                  x =  -0.87 / -0.29

                  x = 3

                  y / -1.16 = 1 / -0.29

                  y = -1.16 / -0.29

                  y = 4

Answer:

                  So the value of x is 3 and y is 4.