Question

решите пж
заранее спасибо

Answer 1

${(3x + 4)}^{2} - (3x - 1)(1 + 3x) = 65 \\ {9x}^{2} + 24x + 16 - (3x - 1)(3x + 1) = 65 \\ {9x}^{2} + 24x + 16 - ( {9x}^{2} - {1}^{2} ) = 65 \\ {9x}^{2} + 24x + 16 - {9x}^{2} + 1 = 65 \\ 24x + 17 = 65 \\ 24x = 48 \\ x = 2$
Формулы:
${(a + b)}^{2} = {a}^{2} + 2ab + {b}^{2} \\ (a - b)(a + b) = {a}^{2} - {b}^{2}$

Answer 2

(3x+4)²-(3x-1)*(1+3x)=65
9x²+24x+16-9x²+1=65
24x+17=65
24x=48   |÷24
x=2.
Ответ: x=2.