Answer:
3p−4q+r) is (p + 7q - 6r)(p+7q−6r) less than (4p+3q-5r)(4p+3q−5r) .
Let (3p-4q+r)(3p−4q+r) is 'x' less than (4p+3q-5r)(4p+3q−5r) . Then
3p-4q+r = 4p+3q-5r - x→3p−4q+r=4p+3q−5r−x
x= 4p+3q-5r - (3p-4q+r)→x=4p+3q−5r−(3p−4q+r)
x= 4p+3q-5r - 3p + 4q - r→x=4p+3q−5r−3p+4q−r
x= 4p- 3p +3q +4q - 5r - r→x=4p−3p+3q+4q−5r−r
x= p + 7q - 6r→x=p+7q−6r
Thus (3p-4q+r)(3p−4q+r) is (p + 7q - 6r)(p+7q−6r) less than (4p+3q-5r)(4p+3q−5r) .