2x^2=4x
I'm pretty sure this is it because there are only 2 like terms so you can't combine anything with 4x.
Sn = a(r^n - 1)/(r - 1)
S4 = 228(4.8^4 - 1)/(4.8 - 1) = 228(530.8416 - 1)/3.8 = 228(529.8416)/3.8 = 120,803.8848 / 3.8 = 31,790.496
Please find attached photograph. The answers are 9a^2 and 15ab.
Step-by-step explanation:
