Question

Розв'яжіть рівняння
(4y-7)(4y+7)-(5+y)²=(5y-7)(8+3y)

Answer 1

$\displaystyle\bf\\(4y-7)(4y+7)-(5+y)^{2} =(5y-7)(8+3y)\\\\\\(4y)^{2} -7^{2} -(5^{2} +2\cdot 5\cdot y+y^{2} )=5y\cdot 8+5y\cdot 3y-7\cdot 8-7\cdot 3y\\\\\\16y^{2} -49-25-10y-y^{2}=40y+15y^{2} -56-21y\\\\\\15y^{2} -74-10y=19y+15y^{2} -56\\\\\\15y^{2} -10y-19y-15y^{2} =-56+74\\\\\\-29y=18\\\\\\y=-\frac{18}{29}$