Question

Решить уравнения 1)(х+5)в квадрате-(х+4)(х-4)=61 2)(х+7)в квадрате-(х-3)в квадрате =140 3 (х+5)в квадрате-(х-5)в квадрате= 45

Answer 1

$1)( x+5)^{2} - (x+4)(x-4)=61\\x^{2} +10x+25-(x^{2} -4^{2} )=61\\x^{2} +10x+25-x^{2}+16=61\\ 10x +41=61\\10x=20\\x=2\\\\2) (x+7)^{2} -(x-3)^{2} =140\\x^{2} +14x+49-(x^{2} - 6x+9)=140\\x^{2} +14x+49-x^{2}+6x-9=140\\20x +40=140\\20x=100\\x=5\\\\3)(x+5)^{2}-(x-5)^{2} =45\\x^{2} +10x+25-(x^{2} -10x +25)=45\\ 20x=45\\x= 2,25$