The lengths of the sides of a triangle are 18 km, 23 km, and 30 km. is the triangle a right triangle, an acute triangle, or an obtuse

a^2 + b^2 = c^2 is right         a^2 + b^2 > c^2 is acute        a^2 + b^2 < c^2 is obtuse

a^2 + b^2 = c^2

18^2 + 23^2 = 30^2

324 + 529 = 900

853 < 900

obtuse

the entire expression should be subtracted from 30. to subtract the quantity, distribute the negative sign, which changes the signs on the terms. so, the –2 changes to positive and gets added to 30 instead of subtracted from it.

hope this ! ^w^

2x^2+5x+17

your welcome. : )