Step-by-step explanation:
I guess, this expression really is
-9k² + 6k² - 7k² - 5k² + -8k² + -2k²
remember : all terms with the same base reference (either a number or a variable with the same exponent, or a function ...) can be combined.
all the terms in this expression are about k². so we can combine them all
k² × (-9 + 6 - 7 - 5 - 8 - 2) =
k² × -25 or simply -25k²
always also remember the rules of combining signs and operations :
++ = +
+- = -
-+ = -
-- = +
