Question

2. Решите уравнение a) (3 + x)(x + 7) - (x + 4)2 = 0 6) (3х+4)2 - (3х-1)(1 + 3х) = 40​

Answer 1

$(3 + x)(x + 7) - (x + 4)^{2} = 0\\3x+21+x^{2} +7x-(x^{2} +8x+16)=0\\3x+21+x^{2} +7x-x^{2} -8x-16=0\\2x+5=0\\x=-\frac{5}{2} \\x=-2,5$

$(3x+4)^{2} - (3x-1)(1 + 3x) = 40\\9x^{2}+24x+16-(3x+9x^{2} -1-3x)=40\\9x^{2}+24x+16-3x-9x^{2}+1+3x=40\\24x=40-1-16\\24x=23\\x=\frac{23}{24}$