Question

If 3x-7y=10 & xy = 1,then the value of 9x²+49y² is ?​

Answer 1

142

Step-by-step explanation:

(3x-7y)^2=9x^2+49y^2-42xy

by putting the values from the problem:

100=9x^2+49y^2-42

9x^2+49y^2=100+42