(3x-8)(7x+5)=(3x-8)^2

Question

(3x-8)(7x+5)=(3x-8)^2

Answer 1

(3x-8)(7x+5)=(3x-8)^2
21x^2+15x-56x-40=9x^2-48x+64
21x^2-41x-40=9x^2-48x+64
21x^2-9x^2-41x+48x-40-64=0
12x^2+7x-104=0
D=49-4*12*(-104)=49+4992=5041=71^2
x1=(-7+71)/24=64/24=32/12=16/6=8/3
x2=(-7-71)/24=-78/24=-39/12=-13/4

Answer 2

(3x - 8)( 7x+5) = (3x -8)^2;
(3x - 8)(7x+5) - (3x-8)(3x-8) = 0l;
 (3x - 8)(7x + 5 - 3x + 8) = 0;
(3x - 8) (4x + 13) = 0;
 3x - 8 = 0; ⇒ 3x = 8; x = 8/3;
4x + 13 = 0; ⇒ 4x = -13; x = - 13/4