x2-7x-30 you have to factor 30 into two numbers such that their product is 30 and difference is 7 if you factor 30, you get 3 and 10 such that 3*10 = 30 and 10-3 = 7 x2 -(10-3)x-30 ------> x2 -10x+3x-30 ...
x2-7x-30 you have to factor 30 into two numbers such that their product is 30 and difference is 7 if you factor 30, you get 3 and 10 such that 3*10 = 30 and 10-3 = 7 x2 -(10-3)x-30 ------> x2 -10x+3x-30 ...
multiply first equation by 3, 3(2x+5y) =3(-9) ...